Background
Maternal low birthweight and vitamin D deficiency in pregnancy are associated with a similar spectrum of adverse pregnancy outcomes including pre‐eclampsia and gestational diabetes. However, the relationship between maternal birthweight and subsequent vitamin D concentrations in early pregnancy is largely unknown.
Methods
We assessed whether self‐reported maternal birthweight was associated with risk of early pregnancy vitamin D deficiency (≤20 ng/mL) among a pregnancy cohort (n = 658). Serum 25‐hydroxyvitamin D [25(OH)D] was measured using liquid chromatography‐tandem mass spectroscopy.
Results
Adjusting for maternal characteristics and month of blood draw, a 100‐g higher maternal birthweight was associated with a 5.7% decreased risk of early pregnancy 25(OH)D deficiency [odds ratio (OR) = 0.94; 95% confidence interval (CI) 0.90, 0.99]. Low‐birthweight (<2500 g) women were 3.7 times as likely to have early pregnancy 25(OH)D deficiency compared with normal‐birthweight women [OR = 3.69; 95% CI 1.63, 8.34]. These relationships were not modified by either pre‐pregnancy overweight status [body mass index (BMI) ≥25 kg/m2] or adulthood weight trajectory (BMI change ≥2 kg/m2 from age 18 to pre‐pregnancy).
Conclusions
Further research on shared developmental mechanisms that determine birthweight and vitamin D homeostasis may help identify targets and related preventative measures for adverse pregnancy and birth outcomes.