Childhood underweight, overweight, and obesity are increasingly rife, which have a substantial impact on adulthood health and quality of life. Globally, over 340 million children and adolescents aged 5–19 are overweight/obese [1
]. In 2018, ∼8% of Australian children aged 5–14 were obese and 12% had overweight [2
]. Childhood underweight, overweight, and obesity are linked with adverse health outcomes throughout the life-span [3
]. For example, overweight/obese children are more likely to become obese adults [4
] and have a greater risk of metabolic, pulmonary, and cardiovascular diseases, including diabetes, hypertension, stroke, and asthma. Childhood obesity diminishes social and emotional functioning, including depression, bullying, and low self-esteem [5
]. Childhood underweight is also a serious public health concern, especially in low and middle-income countries, which has been linked with a greater risk of infectious diseases and leads to overweight and obesity in adulthood [7
Maternal nutrition could affect offspring body composition or weight outcomes through epigenetic changes and the establishment of the gut microbiome in the fetus [9
]. The maternal diet is also the key source of energy for the baby, which has been associated with the risk of offspring obesity [10
]. Over the past decade, researchers have provided pertinent information on the relationship between maternal diets in pregnancy and offspring body compositions. Currently, however, researchers have shown a growing interest in examining the impacts of maternal diet before pregnancy on offspring body mass index (BMI) outcomes since the preconception diet plays a critical role in successful pregnancy outcomes and child health. The baby is fully formed by the end of the 12th week of pregnancy, as well as fetal tissue growth and developments are being programmed [12
]. A pre-pregnancy diet has, therefore, a significant role in the successful development of a pregnancy and is likely to have a substantial impact on offspring outcomes. A study conducted by Stephenson et al. showed that nutritional intervention in pregnancy might ameliorate maternal health with a modest effect on adverse birth outcomes, but no latter impact on offspring health [13
]. Maternal nutrition in pregnancy relies on the availability of micronutrient reserves, that is, stores of certain nutrients before pregnancy, including iron and calcium. Keeping adequate preconception nutrition, therefore, has a critical role in ensuring a good nutritional status in the pregnancy period and child health [14
A considerable amount of literature has been published on the relationship between maternal diet in pregnancy and childhood body compositions or BMI outcomes, including overweight and obesity; however, the findings have been inconsistent [15
]. A prospective cohort study conducted by Strohmaier et al. reported no association between peri-conception healthy dietary patterns and obesity risk in their offspring [19
]. No study, to our knowledge, has conducted the relationship between pre-pregnancy diet quality and a child’s BMI outcomes in offspring.
The current study set out to examine the association between pre-pregnancy diet quality and childhood BMI outcomes aged 2–12 years using data from a nationally representative longitudinal study of Australian mothers and children. We hypothesized that maternal diet quality before pregnancy would be associated with a decreased risk of childhood underweight and overweight/obesity. The study also investigated the interaction effects of pre-pregnancy BMI in the relationship between preconception diet quality and offspring BMI.
This study included 1936 mothers with 3391 children (mean age 7.4 years, SD 2.9) using the ALSWH and the MatCH study (Figure 1
). Of the 3391 children, 391 (11.5%) were categorized as underweight, 424 (12.5%) as overweight, and 111(3.3%) as obese. The median period between the maternal FFQ survey and childbirth was 3.4 (IQR 2.9). The mean age of mothers at birth was 33.1 (SD 2.9) years.
As shown in Figure 2
, women had good adherence to fruits, added sugar, total protein, and greens and beans, while they had low adherence to sodium consumption, saturated fats, fatty acids, and seafood and plant protein. The mean pre-pregnancy HEI-2015 score was 58.1 (SD 12.3). The HEI-2015 score had a strong inverse correlation with glycemic index (r
= −0.5), glycemic load (r
= −0.3), all fats (r
= −0.4), and saturated fats (−0.5).
A significantly higher proportion of childhood obesity was found among mothers with the lowest income, education, and obesity (Table 1
). Underweight children are also more likely to be born to mothers with the lowest income and smokers. LBW children are more likely to be underweight and obese, compared to the normal BMI category. There was also a higher percentage of offspring obesity and underweight among children raised without breastfeeding. Childhood obesity was more likely to occur among children with high consumption of sweetened beverages.
compares the distribution of HEI-2015 score before pregnancy over offspring BMI categories. The mean HEI-2015 score was lowest among obese (55.1 points) and underweight (56.7 points) children.
As can be seen from Table 2
, there was a greater adherence to diet quality among older, urban residents, and well-educated women. Women with better adherence to maternal diet quality had also greater household income and performed higher physical activity.
provides the relationship between pre-pregnancy diet quality and offspring BMI categories. In all models, women with the lowest quartile of HEI-2015 score and children with normal weight are used as reference groups. We found children of mothers with a greater quality of diet had a reduced risk of underweight and obesity compared to children of mothers with lower diet quality after adjustments for important potential confounders and covariates. Greater adherence to pre-pregnancy HEI-2015 score was associated with decreased the risk of childhood underweight, highest vs. lowest quartile (RRR = 0.68, 95% CI: 0.49, 0.96), p
= 0.03. Maternal diet quality was also inversely associated with the risk of offspring obesity. Compared with Quartile 1, women in Quartile 4 of the HEI-2015 score had a lower risk of childhood obesity after adjusting for potential confounders, including maternal education, smoking status, physical activity, household income, child diets, sex, age, and breastfeeding status (RRR = 0.49, 95% CI: 0.24, 0.98), p
= 0.04. However, the association was not remained significant after adjusting for pre-pregnancy BMI (RRR = 0.54, 95% CI: 0.26, 1.11), p
This study also assessed the relationship between each dietary component of HEI-2015 scores before pregnancy and childhood BMI categories (Table 4
). Better adherence to sodium consumption was strongly associated with reduced risk of childhood overweight and obesity after fully adjusting for maternal and child characteristics (RRR = 0.18, 95% CI: 0.14, 0.23) and (RRR = 0.21, 95% CI: 0.17, 0.26), respectively, p
< 0.0001. Higher adherence to seafood and plant proteins component was also inversely associated with risk of childhood underweight (RRR = 0.84, 95% CI: 0.73, 0.99), p
The study examined whether the association between preconception HEI-2015 score and childhood BMI categories differed by pre-pregnancy BMI using an interaction model (Supplemental Table S1
). The association between preconception diet quality and child BMI categories was not modified by pre-pregnancy BMI before and after adjusting for potential confounders.
Further sensitivity analysis showed that maternal diet quality was reasonably stable from before pregnancy to during pregnancy (Supplementary Table S2
). There was a slight mean increase, 1.3 points SD (12.3) in the HEI-2015 score between before and during pregnancy, however, the mean change was not statistically significant (p
This study was designed to investigate the relationship between maternal diet quality before conception and childhood BMI outcomes. We found that higher adherence to maternal diet quality before pregnancy was associated with a reduced risk of offspring being obese and underweight.
To our knowledge, this is the first evidence conducted on the association between preconception diet quality and offspring BMI outcomes in Australia. Our finding is contrary to that of Strohmaier et al. (2020) who found no relationship between healthful dietary intake during peri-conception and offspring obesity aged 12–23 years [19
]. This inconsistency might be due to the difference in quality and quantity of maternal diets, the timing of the intake, offspring age, and the assessment techniques used. For example, Strohmaier et al. used Alternate Healthy Eating Index, (AHEI), Alternate Mediterranean Diet, and Dietary Approach to Stop Hypertension, to assess maternal diet quality. The offspring BMI was also categorized according to the International Obesity Task Force and WHO guidelines.
In reviewing the literature, several pieces of evidence have been documented in the relationship between women’s dietary consumption in pregnancy and childhood obesity [35
]. However, no evidence was reported in the relationship between women’s diet quality and childhood underweight. Martin et al. observed a positive association between dietary patterns in pregnancy, characterized by white bread, processed and red meats, and French fries and offspring BMI-for-age z score in the first 3 years of life [35
]. In a cross-generational cohort study conducted in Ireland, maternal intake of processed diets, characterized by chips, crisps, sweets, and chocolate, and processed meat was also significantly associated with increased risk of offspring overweight/obesity at age of 5 years [36
]. On the other hand, Fernández-Barrés et al. reported higher adherence to Mediterranean dietary patterns, characterized by fruits, vegetables, legumes, nuts, cereals, olive oil, fish, dairy, and meat was associated with decreased risk of offspring abdominal obesity [37
]. Chen et al. also reported that maternal dietary patterns, characterized by higher consumptions of vegetables and fruits and lower consumption of fast diet were associated with lowering the risk of child adiposity [38
]. A Spanish birth cohort study reported a null association between Mediterranean diets and child BMI-Z score [37
]. Dhana et al. also reported no association between women’s dietary quality explored by AHEI-2010 score and risk of childhood obesity [39
]. In summary, there were inconsistent findings observed results in the assessment of maternal diets and offspring BMI. The discrepancies might be due to a large variation of women’s dietary consumptions, including the quantity and quality of diets. There was also variation in sample size, study design, and dietary assessment technique across the studies.
Maternal nutrition may affect early epigenetic changes and establishment of the gut microbiome in the fetus, which results in altered gene expression on adipogenesis leading to obesity and metabolic disease in offspring [9
]. For example, in an animal study, Aagaard-Tillery et al. showed that maternal high-fat diets could change fetal chromatin structure and subsequent to increased recruitment of transcription factors to the target DNA binding sites through altering histone modification [40
]. The high-fat diets could also affect fetal gut microbiome profiles, which contributes to the risk of offspring obesity [41
]. Many studies showed that certain bioactive dietary components have a crucial role in influencing epigenetic modulation, known as “epigenetic diets”, including methyl donors (e.g., vitamin B12 and folate) source of diets, soybean isoflavone, broccoli sprouts, and green tea polyphenols [42
]. Pre-pregnancy is the most critical period for epigenetic modulation since the immediate maturation of sperm and egg occurs during this period [44
]. We, therefore, hypothesized that preconception diet quality would have a substantial influence on offspring weight outcomes.
Pre-pregnancy diet quality plays a vital role in proper fetal growth and development because the first trimester of gestation is a critical period for fetal and placental tissue developments [45
]. A greater HEI-2015 score indicates a higher quality of dietary consumptions, including anti-inflammatory nutrients or antioxidants, unsaturated fats, and dietary fibers, and lower consumptions of saturated fats, sodium, refined grain, and added sugars. In the current study, the HEI-2015 score had also a strong inverse correlation with glycemic load, glycemic index, all fats, and saturated fats. Such a healthy dietary pattern might, therefore, have a beneficial role in childhood healthy weight outcomes.
Another important finding was that higher adherence to sodium intake was strongly linked with lowering the risk of childhood overweight and obesity, in which mothers with lower sodium consumption received greater scores. So far, no studies provide clear evidence that higher adherence to maternal sodium intake reduces the risk of childhood overweight/obesity. However, much evidence has shown that a greater sodium intake is linked with an increased risk of overweight/obesity [46
]. A diet high in sodium enhances alteration of insulin and glucose metabolism which favors fat accumulation, subsequently increases adipose tissue mass [48
]. Sodium intake also induces appetite and thirst and rises extracellular volume and energy intake, which contribute to overweight/obesity [49
]. We have also observed that greater adherence to seafood and plant protein components was linked with a reduced risk of childhood underweight. Seafood and plant proteins are rich in high-quality proteins, n-3 polyunsaturated fatty acids, fiber, and essential micronutrients. These nutrients have a vital role in child growth and development, and healthy bodily compositions [51
]. This finding is an important area for future research.
In the present study, the relationship between pre-pregnancy diet quality and offspring obesity was attenuated by pre-pregnancy BMI. Stuebe et al. [34
] documented that pre-pregnancy BMI was a strong risk factor of offspring obesity. In our study, the pre-pregnancy BMI was also strongly linked with a child’s obesity in offspring. However, the association between preconception diet quality and childhood obesity did not vary by pre-pregnancy BMI. Further studies, therefore, could usefully explore the mediating effects of pre-pregnancy BMI in the relationship between preconception diet quality and offspring obesity.
This study has several strengths, including using a population-based prospective cohort study, a large sample size, and information on a wide range of potential confounders and covariates. The study used the HEI-2015 score to measure the pre-pregnancy dietary quality, which is a contemporary index of dietary quality where each component is calculated based on a density of 1000 Kcal. The HEI-2015 score assesses dietary quality rather than quantity. A validated and semi-quantitative FFQ was used to explore women’s dietary consumptions, which was designed for use in the Australian community. Further sensitivity analysis was performed to examine the stability and changes in women’s dietary quality from before to during pregnancy. In the current study, the HEI-2015 score was stable from before to during pregnancy, and no significant mean differences in the scores were observed at the two-time points. The study utilized data from a nationally representative cohort study of Australian women and children. The current findings, therefore, could be applicable to other populations. However, the present study was limited by the use of self-report data on women’s diets and offspring weight and height, which might have information bias and measurement error. The 101 food items were constructed according to women’s reports of dietary consumption over the previous 12 months, which might create a recall bias. Another limitation might be a long-time period between the outcome (offspring BMI between ages 2 and 12) and exposure (maternal diets). Some exposures/events might be occurred in this time window to influence offspring weight outcomes. Though this study controlled several potential confounders, there might be residual confounding, for example, micronutrient supplementation, which might alter the results.