Important Role of Pregnancy Planning in Pregnancy Outcomes in Type 1 Diabetes

Abstract

Background/Objectives: Compared to in the general pregnant population, pregnancy in women with type 1 diabetes (T1D) is still associated with an increased number of perinatal complications affecting both the fetus and the mother. The Great Orchestra of Christmas Charity Foundation (GOCCF) program enables the use of continuous subcutaneous insulin infusion (CSII) enhanced by a hypo-stop function and real-time continuous glucose monitoring (rtCGM) during the preconception or early pregnancy period in patients with T1D. This observational study aimed to analyze the association between pregnancy planning and pregnancy outcomes in patients who qualified for the GOCCF program. Methods: Ninety-eight women with T1D, aged 21–41 years, who began using the CSII + rtCGM system at the planning/early pregnancy stage or at a later stage in the case of an unplanned pregnancy, were eligible for this study. We analyzed glucose control, the insulin requirements, the pregestational BMI, the maternal weight gain, the occurrence of preterm births, congenital malformations and the birthweight of newborns. Results: Women who planned their pregnancies had significantly better glycemic control before and throughout the entire pregnancy, and a significantly higher proportion of them achieved a TIR (time in range) > 70% (58.7% vs. 28.9%, p = 0.014) and TAR (time above range) < 25% (65.2% vs. 24.4%, p < 0.001). Their glucose variability at the end of the pregnancy was significantly lower (29.4 ± 5.5 vs. 31.9 ± 5.1, p = 0.030). They also gave birth later, at a mean of 37.8 ± 0.9 weeks compared to 36.9 ± 1.8 weeks in the non-planned group (p = 0.039). Preterm birth occurred in five women (10.4%) who planned their pregnancies and in fifteen women (30%) who did not, with p = 0.031. Conclusions: Pregnancy planning in women with type 1 diabetes (T1D) is associated with better glucose control before conception and throughout the entire pregnancy, resulting in better pregnancy outcomes.

1. Introduction

The prevalence and incidence of type 1 diabetes (T1D) have increased significantly in recent years. In the pediatric population in north-east Poland, its incidence increased from 19.48 to 36.68 per 100,000 people per year between 2010 and 2022 [1]. In the Subcarpathian region in south-east Poland, where our study was conducted, the number of people under 40 years of age with type 1 diabetes now exceeds 4500 (data obtained from the regional branch of the National Health Fund, unpublished). Therefore, the number of women of reproductive age with T1D has also increased substantially. This has resulted in a growing number of pregnancies in females with pregestational T1D, with the prevalence increasing to one in every 275 pregnancies [2,3]. Despite continuous progress in the care of pregnant women with T1D, pregnancy in such patients remains a significant medical problem. It is responsible for an increased number of perinatal complications affecting both the fetus and the mother. These complications include miscarriages, perinatal death, congenital malformations, preterm births, large-for-gestational-age (LGA) neonates and macrosomia, which have a higher incidence compared to that in the general pregnant population [4,5]. According to the clinical practice recommendations of Diabetes Poland, pregnancies in women with type 1 diabetes should be planned in order to avoid adverse outcomes for both the mother and child. Preconception care should include optimizing diabetes therapy, with an HbA1c level of less than 6.5% (48 mmol/mol) ideal prior to conception. An assessment of the presence of possible diabetic complications should be carried out, including an ophthalmological examination at the stage of pregnancy planning or in the first trimester at the latest. Diabetes education should also be provided, including dietary advice, as well as an assessment of thyroid function [6].

The multicenter, international, randomized and controlled CONCEPTT trial was the first to prove that using a continuous glucose monitoring system (CGM) during pregnancy is associated with better glucose control and better pregnancy outcomes than self-monitoring of blood glucose (SMBG) [7]. The wider introduction of new technologies in diabetes care, such as CSII and CGM systems—either those employing intermittently scanned (isCGM) or real time CGM (rtCGM)—has substantially improved the metabolic control and pregnancy outcomes in women with pregestational T1D [8,9]. The Great Orchestra of Christmas Charity Foundation (GOCCF) program offers free rental of insulin pumps and rtCGM systems (SAP—sensor-augmented pump) with a PLGS (predictive low-glucose suspend system) from the preconception stage to women with T1D who are planning to become pregnant.

As mentioned earlier, pregnancies in women with T1D should be planned [6]. Unfortunately, the number of unplanned pregnancies in this population is still too high in real life. Interestingly, the number of papers assessing the impact of pregnancy planning on the outcomes is low. Although their results have been somewhat discordant, they indicate better glycemic control and better pregnancy outcomes, particularly a lower number of preterm deliveries, in women who plan their pregnancies compared to those who do not [10,11]. Therefore, we conducted a retrospective, observational, single-center study to analyze the impact of pregnancy planning on the outcomes for patients who qualified to participate in the GOCCF program.

2. Materials and Methods

2.1. Study Population

The Diabetic Outpatient Clinic at the University Clinical Hospital (UCH) in Rzeszów is currently the only center in the Subcarpathian region to participate in the GOCCF program. Between 2018 and 31 March 2025, 102 women with T1D were enrolled in the GOCCF program. Four of them were excluded from the final analysis: two had not been diagnosed with T1D during gestation; one suffered from adrenal insufficiency (Addison’s disease); and the last had advanced diabetic complications at the time of conception, including diabetic kidney disease in stage G4. This led to the development of preeclampsia, and the pregnancy was terminated prematurely by cesarean section in the 28th week. All the remaining women were included in the analysis.

Of the 98 women aged 21–41 years included in the analysis, only 48 (49.0%) had planned their pregnancies, while 50 (51.0%) had not. A pregnancy was defined as planned if the patient had undergone an eye fundus examination up to one year before gestation and laboratory tests, including hematology, HbA1c tests and thyroid and kidney function assessments, as well as any other tests required before pregnancy. Twenty-three women under the care of the Diabetic Outpatient Clinic at the UCH received an SAP with a PLGS system before conception, following training during the pregnancy planning stage. This training consisted of three steps. First, a certified dietitian with a master’s degree provided training on the diet and recommended physical activity during pregnancy. Then, a certified educational nurse trained the patient in the technological aspects of operating the insulin pump, connecting tubes, filling the insulin reservoir, etc. Finally, a doctor trained the patient on the target glucose values, setting insulin doses into entering them into the application, adjusting the insulin doses according to the current glucose level and how to react to high and low glucose concentrations. Patients referred from other diabetic centers in the Subcarpathian region were considered to be planning a pregnancy if they had received pre-pregnancy counseling at their centers and had undergone the above-listed procedures. These data were assessed during the first visit based on information provided by the patient and medical documentation. These patients were often unfamiliar with the use of CSII and rtCGM. Therefore, they had to undergo the aforementioned training, which took 1–2 weeks. They then received an SAP with a PLGS system, usually at 8–12 weeks of gestation (depending on the pump availability, as there were limited numbers). This explains the later initiation of CSII in some women, despite their pregnancy being planned. The baseline characteristics of the study participants are presented in

Table 1. Baseline characteristics of study participants, N = 98.

Parameter	Mean/n	SD/%
Age (years)	29.9	4.1
T1D duration (years)	14.4	7.7
Pregestational BMI (kg/m2)	24.90	4.23
Pregestational HbA1c (mmol/mol)	54.4	11.4
Pregestational HbA1c (%)	7.12	1.04
CSII + CGM initiation (week)	8.6	6.3
CSII use before pregnancy (n)	33	33.7%
White’s scale:
A/B	24	24.5
C	51	52.0
D	19	19.4
R/F/RF	4	4.1

SD—standard deviation; T1D—type 1 diabetes; CSII—continuous subcutaneous insulin infusion; CGM—continuous glucose monitoring.

.

2.2. Management of Diabetes

After qualifying for the GOCCF program, the patients were trained regarding use of SAPs with a PLGS system as described earlier. The GOCCF provided MiniMed 640G personal insulin pumps and later also MiniMed 740G pumps (Medtronic, Minneapolis, MN, USA). During pregnancy the patients were treated in accordance with the current Diabetes Poland clinical practice recommendations, with a target HbA1c level < 6.5% (<48 mmol/mol) in the first trimester and <6.0% (<42 mmol/mol) in subsequent trimesters, a target range of CGM glucose values of 3.5–7.8 mmol/L (63–140 mg/dL), a TIR > 70%, a TAR < 25% and a TBR (time below range) < 4%, with a glucose level < 3 mmol/L (54 mg/dL) <1.0% of the time [6].

2.3. Analyzed Outcomes

The analyzed parameters included the participant’s age; the diabetes duration; the pregestational BMI; the pregestational treatment (CSII or MDI); the HbA1c level before gestation and in each pregnancy trimester; CGM parameters including the TIR (time in range), TAR (time above range), TBR (time below range) and CV (coefficient of variation); insulin requirements; the maternal weight gain; miscarriages; preterm delivery; method of termination of the pregnancy; congenital malformations; and the birthweight of newborns: normal, LGA or SGA (large or small for gestational age) and macrosomia (birthweight > 4000 g).

2.4. Statistical Analysis

Statistical analysis was performed using SigmaPlot for Windows software, version 12.5 (Systat Software Inc., San Jose, CA, USA). The continuous variables are presented as the mean and standard deviation (SD). The nominal variables are presented as absolute and percentage values. The normality of the data distribution was checked using the Shapiro–Wilk test. The differences between baseline and end-of-study values within the groups were analyzed using a paired two-tailed Student’s t-test for dependent variables or a Mann–Whitney rank sum test where appropriate, while the differences between the groups were analyzed using an unpaired two-tailed Student’s t-test for independent variables or a Mann–Whitney rank sum test where appropriate. The categorical variables were analyzed using the χ² test with Yates continuity correction applied. A p value < 0.05 was considered significant.

3. Results

3.1. Whole Group

3.1.1. Metabolic Control

After initiation of SAP therapy with a PLGS system, the glucose control (HbA1c level, TIR and TAR) improved substantially (

Table 2. Baseline (pregestational/first visit) and last visit values for the whole group.

Parameter	Baseline		Last Visit		p Value
	Mean	SD	Mean	SD
HbA1c (mmol/mol)	54.4	11.4	43.2	8.6	<0.00001
HbA1c (%)	7.12	1.04	6.10	0.78	<0.00001
TIR (%)	61.7	14.1	68.4	13.4	0.00001
TAR (%)	33.7	15.5	28.0	14.3	0.0006
TBR (%)	4.6	4.6	3.7	4.5	0.027 *
CV (%)	34.1	6.2	30.6	5.4	<0.00001
Body weight (kg)	68.0	12.3	80.4	12.3	<0.00001
Daily total insulin dose (IU)	39.8	13.9	73.0	28.1	<0.00001
Daily total insulin dose (IU/kg)	0.59	0.19	0.90	0.27	<0.00001

TIR—time in range; TAR—time above range; TBR—time below range; CV—coefficient variability; * statistical power < 0.800.

). Only 31.2% of the women had an HbA1c level below 6.5% (48 mmol/mol) before pregnancy, which increased to 54.1% in the first trimester. In the second and third trimesters, 55.1% and 51.5% of women achieved an HbA1c level of <6.0% (<42 mmol/mol), respectively. A TIR > 70% and TAR < 25% were achieved by 44.0% and 45.0% of the women, respectively (30.1% and 31.2%, respectively, at the first visit after CSII initiation). The TBR decreased significantly, especially the time below 3.0 mmol/L (54 mg/dL), which fell from 2.0 ± 2.8% to 1.3 ± 2.0% (p = 0.009).

3.1.2. Weight Gain and Birthweight

One important issue for women with type 1 diabetes (T1D) who are pregnant is excessive weight gain during pregnancy. The mean weight gain for the whole group was 12.4 ± 4.7 kg. Weight gain higher than that recommended for a given pregestational BMI occurred in 29 women. In 51 cases, the weight gain was within the recommended range, while in 18 women, it was lower than recommended. The proportion of LGA babies in these groups was significantly different: 48.3%, 21.6% and 27.8%, respectively (p = 0.043). The mean birthweight of the newborns also differed significantly between these groups. It was highest in the group with excessive weight gain: 3824.1 ± 510.3 g versus 3481.5 ± 612.9 g (normal weight gain), p = 0.024, and versus 3333.9 ± 706.0 g (insufficient weight gain), p = 0.033.

According to the recommendations of the Polish Society of Gynecologists and Obstetricians, an attempt should be made to induce labor after the 38th week of pregnancy in women with diabetes. If there is no progress in labor or other indications occur, the pregnancy should be terminated by cesarean section (CS) [12]. In our study, 87.8% of the pregnancies were terminated by cesarean section, and the decision regarding the method of termination was made by obstetricians. A total of 20 women experienced preterm birth. Macrosomia occurred in 21 newborns, and 30 babies (30.6%) were LGA. None of the newborns were SGA. Congenital abnormalities occurred in five newborns: cardiomyopathy in three cases, kidney agenesis in one case and hypospadias in one male newborn.

3.1.3. Insulin Dose

The mean total increase in the insulin dose was 33.2 ± 22.4 IU, and the average increase in the insulin dose per kg of body weight was 0.31 ± 0.25 IU/kg. The highest daily insulin dose increase was found in the group with excessive weight gain: 44.6 ± 25.1 IU. This increase was significantly higher than that in the group with normal weight gain (29.9 ± 21.3 IU, p = 0.004) and in the group with insufficient weight gain (24.3 ± 12.3 IU, p = 0.001). The increases in the insulin dose per kg of body weight in these three groups were not significantly different: 0.39 ± 0.27 IU/kg, 0.27 ± 0.26 IU/kg and 0.29 ± 0.16 IU/kg, respectively (p = 0.110). However, we found a highly significant relationship between the insulin dose per kg of body weight and the birthweight of the newborns (Figure 1A). This also remained significant after correction for the weight gain and baseline HbA1c. In mothers who delivered LGA babies, the mean increase in the insulin dose was 0.44 ± 0.26 IU/kg vs. 0.25 ± 0.22 IU/kg in women who delivered normal-weight newborns (Figure 1B).

3.2. Planned vs. Unplanned Pregnancy

Among the patients enrolled in the GOCCF program, 48 women planned their pregnancies, while 50 pregnancies were unplanned. The women who planned their pregnancies had significantly lower HbA1c levels before gestation, and they began using an SAP with a PLGS system earlier. There were no significant differences between the groups regarding the patients’ age (although it tended to be higher in the pregnancy planning group), duration of T1D, pregestational BMI, body weight, use of CSII before gestation, White’s scale and insulin dose at baseline (

Table 3. Baseline (pregestational/first visit) characteristics of study groups.

Parameter	Pregnancy Planned		Pregnancy Unplanned		p Value
	Mean/n	SD/%	Mean/n	SD/%
Age (years)	30.7	3.8	29.2	4.4	0.076
T1D duration (years)	13.5	8.1	15.3	7.2	0.238
Body weight (kg)	67.8	11.4	68.2	13.2	0.901
Pregestational BMI (kg/m2)	24.46	3.88	25.33	4.56	0.458
Underweight (n)	3	6.3%	2	4.0%	0.782
Normal weight (n)	27	56.3%	27	54.0%
Overweight (n)	12	25.0%	17	34.0%
Obesity (n)	5	10.4%	4	8.0%
CSII + CGM initiation (week)	5.3	5.6	11.8	5.3	<0.00001
CSII before pregnancy (n)	19	39.6%	14	28.0%	0.318
White’s scale:					0.075
A/B (n)	15	31.3%	9	18.0%
C (n)	27	56.3%	24	48.0%
D (n)	5	10.4%	14	28.0%
R/F/RF (n)	1	2.1%	3	6.0%
HbA1c (%)	6.79	0.63	7.52	1.28	0.007
HbA1c (mmol/mol)	50.8	6.9	58.7	14.0	0.007
Daily total insulin dose (IU)	39.8	15.1	39.7	12.7	0.979
Daily total insulin dose (IU/kg)	0.58	0.16	0.60	0.21	0.974

SD—standard deviation; CSII—continuous subcutaneous insulin infusion; CGM—continuous glucose monitoring.

).

3.2.1. Maternal Outcomes

As shown in Figure 2, the women who planned their pregnancies had significantly better diabetes control, as measured using the HbA1c level, before and throughout pregnancy compared to the women who did not plan their pregnancies. These women also had a higher mean TIR and lower TAR when beginning to use an SAP with a PLGS system, and these differences were maintained throughout their pregnancy (p < 0.001 in each case). However, no difference was found regarding the TBR (Figure 3). Nevertheless, the time spent in hypoglycemia below 3.0 mmol/L (54 mg/dL) exceeded the recommended threshold of 1.0% in both the groups.

Table 4. Proportion of women achieving HbA1c and CGM therapeutic targets.

Parameter	Pregnancy Planned		Pregnancy Unplanned		p Value
	n	%	n	%
First visit after SAP initiation
TIR > 70%	20	43.5	8	17.0	0.011 *
TAR < 25%	21	45.7	8	17.0	0.006
Last visit before delivery
TIR > 70%	27	58.7	13	28.9	0.014 *
TAR < 25%	30	65.2	11	24.4	<0.001
HbA1c
Pregestational < 6.5% (48 mmol/mol)	14/42	33.3	10/35	28.6	0.840
First trimester < 6.5% (48 mmol/mol)	34/47	72.3	18/49	36.7	<0.001
Second trimester < 6.0% (42 mmol/mol)	34/48	70.8	20/50	40.0	0.004
Third trimester < 6.0% (42 mmol/mol)	29/48	60.4	21/49	42.9	0.127

TIR—time in range; TAR—time above range; TBR—time below range; CV—coefficient variability; * statistical power < 0.800.

presents the proportion of women with recommended metabolic control of diabetes before pregnancy, the number of women who achieved and maintained the recommended HbA1c values in each trimester, and the number and proportion of women who achieved a TIR > 70% and TAR < 25%. The proportion of women who spent more than 1% of the time below 54 mg/dL was similar in planned and unplanned pregnancies: 13 (27.1%) and 14 (28.0%), respectively (p = 0.901). Women who planned their pregnancies had a lower coefficient variability (CV) than those who did not: 29.4 ± 5.5 vs. 31.9 ± 5.1, p = 0.030. There were no significant differences in the weight gain or increase in the insulin dose, either in total or in IU per kg of body weight, between women who planned and those who did not plan their pregnancies (

Table 5. Gestational weight gain and insulin dose increase in the study groups.

Parameter	Pregnancy Planned		Pregnancy Unplanned		p Value
	Mean/n	SD/%	Mean/n	SD/%
Weight gain (kg)	12.7	4.8	12.1	4.7	0.494
Daily total insulin dose increase (IU)	32.4	19.7	34.0	24.9	0.918
Daily total insulin dose increase (IU/kg)	0.31	0.23	0.31	0.27	0.946

).

3.2.2. Neonatal Outcomes

The most common adverse pregnancy outcome affecting offspring is an excessive birthweight, which manifests as macrosomia and the delivery of LGA babies. In our study, we found no differences in these outcomes between women who planned their pregnancies and those who did not. There were 11 and 10 cases of macrosomia, respectively (22.9% vs. 20.0%, p = 0.916), and 14 and 16 LGA babies, respectively (29.2% vs. 32.0%, p = 0.932). The birthweight was also not significantly different: 3,628 ± 555 g vs. 3,486 ± 683 g (p = 0.261). However, the number of preterm deliveries was significantly lower in women who planned their pregnancies (n = 5, 10.4%) than in those who did not plan their pregnancies (n = 15, 30.0%), with p = 0.031. The mean duration of the pregnancy was also significantly different (37.8 ± 0.9 weeks vs. 36.9 ± 1.8 weeks, p = 0.039). Congenital abnormalities were rare, affecting one neonate in the pregnancy planning group (cardiomyopathy) and four in the non-planning group (two cases of cardiomyopathy, one case of kidney agenesis and one case of hypospadias).

4. Discussion

Despite continuous progress in the treatment of T1D, pregnancy remains challenging for women with T1D. The number of adverse pregnancy outcomes, including maternal and neonatal outcomes (e.g., preeclampsia, preterm delivery, miscarriages, congenital defects, LGA neonates), remains high compared to the prevalence in women without diabetes [13]. Achieving and maintaining good metabolic control, especially during the first weeks of pregnancy, is crucial for improving the pregnancy outcomes. This can be achieved using technology and behavioral treatment, including an appropriate diet and adequate physical activity [14]. Several years ago, the Great Orchestra of Christmas Charity Foundation initiated a program to support pregnant women with type 1 diabetes. The program offers them the free rental of personal insulin pumps and an rtCGM with a PLGS system to improve the efficacy and safety of treatment by avoiding hypoglycemic episodes [15]. This program represented significant progress in the care of pregnant women with T1D in Poland. The Diabetic Outpatient Clinic at the University Clinical Hospital in Rzeszów has participated in this program since 2018. As of March 2025, 102 pregnant women with T1D had received SAP therapy with a PLGS system.

In our retrospective, single-center study, we aimed to analyze whether planning a pregnancy in patients with T1D using continuous subcutaneous insulin infusion (CSII) and rtCGM with a PLGS system from the beginning of gestation, or even from the preconception period, impacts the pregnancy outcomes in these patients. The number of studies addressing this issue is small. Furthermore, none of these studies have used CSII with rtCGM for all the participants. Given this, our study, which was conducted with patients receiving modern SAP therapy with a PLGS system, can be considered innovative.

One of the earliest studies on this topic, also conducted in Poland, found that pregnancy planning was associated with better glycemic control during pregnancy, regardless of the method of insulin therapy—CSII vs. MDI (multiple daily insulin injections) [16]. This study did not use CGM systems. Despite a higher number of neonatal complications in the unplanned pregnancy group, the difference did not reach statistical significance. The authors also noted a significantly greater weight gain in the CSII group compared to the MDI group. Unlike our study and many other papers, a Finnish study conducted in North Karelia found that pregnancy planning was associated with several benefits. Apart from better metabolic control, the number of congenital anomalies was lower, and fewer cesarean sections were performed on women who planned their pregnancies. This study did not use CSII or CGM [17]. Similarly to our observations, the authors of a recent study conducted in Italy and France found that pregnancy planning was associated with lower HbA1c levels throughout the entire gestational period compared to those in unplanned pregnancies. Also, as in our study, the number of preterm deliveries was significantly lower in women who planned their pregnancies. No other differences between the two groups were found. Unlike our study, the authors did not assess changes in the body weight or insulin doses, and such data are unavailable. Moreover, rtCGM was used by very few patients [11]. A study conducted in Poland involving 209 females with T1D treated with either CSII or MDI found that pregnancy planning was not associated with better pregnancy outcomes despite having an association with better metabolic control before gestation and in the first trimester of pregnancy. However, the authors found that a lack of pregnancy planning and a high HbA1c level in the first trimester were independent predictors of macrosomia and LGA infants [10]. In a large study conducted in Spain involving 425 women with pregestational diabetes (306 with T1D), the authors found that, although pregnancy planning was associated with better metabolic control, there were no significant differences between the groups regarding the obstetric and neonatal outcomes. Similarly to our study, there was no significant difference in the weight gain or increase in the insulin dose between the groups of women who planned and did not plan their pregnancy [18]. Another study by the same authors found that a lack of pregnancy planning and elevated HbA1c levels before pregnancy and in the first trimester were associated with a significantly higher risk of fetal hypertrophic cardiomyopathy, diagnosed in 5.8% of neonates [19]. Three such cases were diagnosed in our study. In all the cases, the HbA1c values were higher than recommended before pregnancy (mean of 8.0%) and during the first trimester (mean of 7.3%). In the first CGM report, all of the patients had a TIR < 50% and TAR > 50%, which could explain this neonatal complication. The pregnancy was planned in one of these cases.

In our study, excessive weight gain (29 out of 98 women) was associated with adverse neonatal outcomes, namely macrosomia and LGA infants. One might expect that, in addition to better metabolic control, planning a pregnancy would also be associated with greater dietary discipline during gestation and lower weight gain during pregnancy. However, in our study, women who planned their pregnancies had similar weight gains to those who did not plan their pregnancies. The increase in the insulin dosage and birthweight were not significantly different between the two groups. A recently published meta-analysis revealed that a high pregestational BMI and excessive gestational weight gain are associated with adverse pregnancy outcomes. An analysis of 18,965 pregnancies in women with type 1 diabetes (T1D) revealed that a preconception BMI of at least 25 kg/m² was associated with a 22% higher risk of perinatal complications, including congenital malformations, preeclampsia and admission to the neonatal intensive care unit. Each additional 1 kg/m² was associated with 3% higher odds of these complications. Excessive gestational weight gain has been associated with adverse neonatal and maternal outcomes, including preeclampsia, cesarean delivery, LGA and macrosomia [20]. Limiting the weight gain during pregnancy can be achieved through behavioral interventions, such as dietary changes and increased physical activity. A systematic review and meta-analysis of such interventional studies documented that lifestyle interventions based on diet and physical activity were associated with reduced gestational weight gain, which was associated with a lower risk of adverse maternal and neonatal outcomes. Although this meta-analysis only included studies of the diabetes-free population, it indicates the need for the widespread implementation of such interventions in routine antenatal care, including for women with T1D [21].

Currently, we are witnessing a paradigm shift in the treatment of diabetes, not only that during pregnancy in women with type 1 diabetes [22]. The first study to compare SAP with closed-loop pump therapy in pregnant women with T1D found that the latter method was associated with better overnight glucose control [23]. Three recently published review papers documented that better glycemic control can be achieved using CGM and hybrid closed-loop (HCL) insulin delivery systems. The first paper addressing this issue emphasized that there is strong evidence documenting improved glycemic control, particularly a better overnight TIR and reduced hypoglycemia, with the use of CGM and advanced HCL (AHCL) systems. Furthermore, this treatment has been associated with improved treatment satisfaction [24]. Another recently published systematic review and meta-analysis of thirteen studies with 450 participants revealed improved glycemic control, as measured using the TIR; a reduced amount of time spent in hyperglycemia; and reduced glucose variability [25]. The third paper was also a systematic review and meta-analysis of 18 studies. The findings were similar to those of the previous two papers, showing an increased overnight TIR and reduced hypoglycemia. However, these improvements did not translate into better short-term maternal and fetal outcomes [26]. Therefore, more evidence is necessary to determine whether such treatment is also associated with better pregnancy outcomes.

Our study has several limitations. The first limitation is its retrospective design. However, this design has certain benefits, as it reflects the effects of treatment conducted in everyday clinical practice, in accordance with the current guidelines and recommendations regarding therapeutic goals. A second limitation of our study is its single-center nature. However, in this case, too, some benefits can be found: the training and treatment were provided by the same personnel using the same rules for insulin dose adjustment and procedures for hypoglycemia and hyperglycemia. The same dietitian provided dietary and behavioral advice to all the patients, and the same nurse educated them on personal insulin pump use. The third limitation is the relatively low number of participants, which was associated with insufficient statistical power in some cases (marked with an asterisk in the tables). However, a post hoc analysis revealed that all the other significant differences had sufficient statistical power. The last limitation is the lack of data regarding the socioeconomic and educational status of the study participants, even though these variables may have impacted metabolic control and the pregnancy outcomes. These variables were not assessed in the aforementioned studies. However, in one retrospective study that incorporated these variables into an analysis, they were found to have no impact on glucose control and pregnancy outcomes [27].

5. Conclusions

Pregnancy planning has been shown to lead to significantly better glycemic control and a lower number of preterm deliveries in pregnant women with T1D. Although it has a relatively small impact on clinically relevant pregnancy outcomes, its importance should not be overlooked. Gestational planning should be recommended for all women of reproductive age with type 1 diabetes (T1D) who are considering motherhood in the future, and it would be reasonable to expand the access to pregestational counseling for all women with T1D of childbearing age and refer them to such counseling on their first visit to the diabetes clinic.

The constant development of modern technologies, including AHCL systems, will undoubtedly impact the future treatment paradigm for pregestational diabetes. However, the impact of these systems on clinically relevant maternal and neonatal outcomes during pregnancy remains to be discovered and confirmed.