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Paternal weight prior to conception and infant birthweight: a prospective cohort study
Ravi Retnakaran1,2,3, Shi Wu Wen4,5,6,7, Hongzhuan Tan7
1Leadership Sinai Centre for Diabetes, Mount Sinai Hospital, Toronto, ON, Canada. ravi.retnakaran@sinaihealth.ca.
Insights
Maternal pre-pregnancy body mass index (BMI) significantly impacts infant birthweight. Paternal pre-pregnancy BMI also influences birthweight, though to a lesser extent, highlighting the importance of both parents' weight status.
Area of Science:
- Reproductive Health
- Pediatrics
- Public Health
Background:
- Maternal pre-pregnancy and pregnancy weight status are known determinants of infant birthweight.
- Previous research has limitations due to not assessing paternal weight status preconceptionally.
- This study addresses this gap by evaluating both maternal and paternal preconception weight.
Purpose of the Study:
- To prospectively assess the association of maternal and paternal preconception body mass index (BMI) with infant birthweight.
- To determine the relative contributions of maternal and paternal BMI to birthweight variations.
- To identify predictors of delivering large-for-gestational-age (LGA) and small-for-gestational-age (SGA) infants.
Main Methods:
- A prospective observational cohort study of 1292 newly-married couples in China.
- Assessment of maternal and paternal body mass index (BMI) prior to conception.
- Statistical analysis adjusted for multiple confounding factors including maternal and paternal characteristics, gestational factors, and infant sex.
Main Results:
- Both maternal and paternal preconception BMI were positively associated with infant birthweight.
- Maternal preconception BMI had a stronger association (42.2g/unit increase) than paternal BMI (10.7g/unit increase).
- Maternal BMI explained 6.2% of birthweight variance, while paternal BMI explained only 0.7%. Maternal BMI was an independent predictor of LGA delivery, but paternal BMI was not.
Conclusions:
- Paternal preconception BMI is associated with infant birthweight, but its impact is modest compared to maternal BMI.
- Maternal weight status preconceptionally is a dominant factor influencing infant birthweight.
- This highlights the importance of preconception counseling for both parents regarding weight management.
Background/Objective:
Previous studies have consistently demonstrated that maternal weight status both before and during pregnancy is associated with infant birthweight. However, a fundamental limitation across this literature remains that previous studies have not evaluated the concomitant impact of paternal weight at conception, owing to the paucity of studies in which fathers were assessed prior to pregnancy. Thus, we established a cohort of preconception couples to prospectively evaluate the associations of maternal and paternal weight prior to pregnancy with infant birthweight at delivery.
Methods:
In this prospective observational cohort study, 1292 newly-married women and their partners in Liuyang, China, were assessed at median of 23.3 weeks before a singleton pregnancy, thereby enabling concomitant assessment of preconception maternal and paternal body mass index (BMI) in relation to infant birthweight.
Results:
Mean birthweight was 3294 ± 450 g with 147 neonates (11.4%) born large-for-gestational-age (LGA) and 94 (7.3%) small-for-gestational-age (SGA). After adjustment for maternal and paternal factors prior to conception (age, education, smoking, BMI, household income), length of gestation, total gestational weight gain, gestational diabetes, preeclampsia, and infant sex, it was noted that infant birthweight increased by 42.2 g (95% CI 29.5-54.8; p < 0.0001) per unit increase in maternal pregravid BMI and 10.7 g (95% CI 0.5-20.9; p = 0.04) per unit increase in paternal pregravid BMI. Maternal pregravid BMI explained 6.2% of the variance in birthweight whereas paternal BMI explained only 0.7%. Independent predictors of LGA delivery were maternal pregravid BMI (aOR = 1.91, 95% CI 1.50-2.44), maternal age (aOR = 1.48, 95% CI 1.09-2.00), and gestational weight gain (aOR = 1.80, 95% CI 1.40-2.30). Paternal pregravid BMI was not independently associated with LGA or SGA.
Conclusion:
Paternal BMI prior to conception is associated with infant birthweight but only modestly so, in contrast to the dominant impact of maternal weight.
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