Is there an association between maternal diet and birth weight for gestational age?

In a recent study published in the Nutrients Journal, researchers examined the eating habits of 667 pregnant women residing in Catania, Italy.

The study used the principal component (PC) clustering approach to determine the association between maternal diet and infant weight at gestational age.

Study: The effect of maternal dietary habits on birth weight for gestational age: results from the MAMI-MED cohort. Image Credit: G-StockStudio/Shutterstock.com

Background

Gestational diabetes mellitus and inadequate gestational weight gain (GWG) are major threats to maternal and neonatal well-being.

Adverse effects for the child include low birth weight (LBW), births too large or too small for gestational age (LGA and SGA), macrosomia, intrauterine growth restriction (IUGR) and premature births (PTB).

Maternal nutrition is one of the most important determinants of neonatal outcomes and can be modified for better neonatal growth and development.

However, data on the impact of maternal dietary habits on birth weight are limited, and most previous studies examining the relationship did not take gestational sex and infant age into account.

About the study

In the present study, researchers assessed the effects of maternal diet on infant birth outcomes.

The study included mother-neonatal dyads from the MAMI-MED study, who had comprehensive data on diet, sociodemography and birth outcomes obtained using questionnaires, including educational level of the mother, employment status, smoking habits and anthropometric data. The body mass index (BMI) before pregnancy was calculated according to the criteria of the World Health Organization (WHO).

GWG was calculated by subtracting self-reported pre-pregnancy body weight from infant birth weight, and its adequacy was derived based on Institute of Medicine (IOM) guidelines. At delivery, data were collected on length of gestation, length of birth and weight.

Study outcomes included preterm birth (PTB, spontaneous delivery before 37.0 weeks) and weight for gestational age [LGA, SGA, or appropriate gestational age (AGA)] using sex-based reference tables.

Food habits over the previous 30 days were assessed using food frequency questionnaires (FFQs). Daily consumption was calculated based on serving size and frequency of intake. Additionally, total calorie consumption was predicted using the United States Department of Agriculture (US) Dietary Intake Database, accessed January 1, 2014, and adapted to food products Italians.

Data were analyzed using a combination of principal component analysis (PCA) and clustering (mainly K-means and hierarchical clustering). Multivariate logistic regression modeling was performed and odds ratios (ORs) were calculated.

Results

Among study participants, a median age of 31.0 years was observed; 51.0% were primiparous, 25.0% were highly educated, and 51.0% were employed. Of the participants, 91.0% did not smoke during pregnancy and their median total caloric intake was 1703.0 kcal. BMI before pregnancy (median) was 23.0 kg/m²and 60.0% of mothers had normal body weight.

Based on the median GWG of 12.0 kg, 39.0% of mothers documented reduced weight gain, while 29.0% documented excessive weight gain. The median gestational week at delivery was 39.0, and most (94.0%) infant births were at term.

Regarding size at birth, median values ​​of 50.0 cm and 3.30 kg were obtained for height and weight at birth, respectively, and 82%, 7.0% and 11.0% of new -born were respectively AGA, SGA and LGA.

Two groups denoting different diets were identified. The first group (158 women) consisted mainly of plant foods (including raw and cooked vegetables, potatoes, soup, legumes, nuts, fruit, wholemeal bread and rice) , white meat, fish, eggs, margarine, butter, tea, and coffee.

The second group (509 women) was characterized by Western eating habits and junk food (high-salt snacks, dips, chips, and sweets), milk, white bread, and olive and vegetable oils.

Regarding nutrients, women in the first group consume more magnesium, folate, vitamin A, vitamin B6 and vitamin C, while women in the second group consume more unsaturated and saturated fatty acids, vitamin B1 and calcium. Younger, less educated women adhered more to the Western diet (second group).

The main estimators of low gestational age births were primiparity and employment status, but not dietary compliance. Newborns of employed mothers had a lower risk of SGA than those of unemployed mothers (OR 0.4).

On the contrary, primiparous females had a greater risk of GAS than those with ≥1.0 previous pregnancies (OR 2.7). Women in the second group showed a higher probability of births at high gestational age (GAG) than women in the first group (OR 2.2).

In addition, the likelihood of LGA increased by 11.0% per unit increase in pregestational BMI (OR 1.1). Younger Italian women had lower quality diets, indicating that their health awareness improves with age.

Highly educated people tend to possess greater knowledge of the risk-benefit ratios of their diets, and therefore education is the most critical socio-demographic factor influencing diet-related decision-making.

Conclusion

Overall, the study results highlighted the association between adherence to Western diets and the likelihood of having LGA newborns.

The likelihood of LGA was 2.20 times higher in women adhering to Western diets than in those following healthier plant-based diets after adjusting for covariates such as GWG and total calorie intake.

Moreover, the odds of LGA increased with increasing BMI values. Further research needs to investigate likely confounding and mediation by type of employment, hours of work, household income, and regular activities to contribute to the scientific literature and inform the development of nutrition policies for pregnant women.