Prepregnancy obesity is an independent risk factor for neonatal vitamin K deficiency at birth

Neonatal vitamin K deficiency (VKD) is a known risk factor for vitamin K deficiency bleeding (VKDB), a potentially life-threatening condition. However, maternal risk factors for VKD at birth remain poorly understood.

This study aimed to identify maternal factors associated with neonatal VKD at birth, with a focus on prepregnancy obesity.

We conducted a retrospective matched case-control study of neonates admitted to our hospital between 2018 and 2023. VKD was defined as serum protein induced by vitamin K absence-II (PIVKA-II) levels ≥1000 mAU/mL on day 0 of life before vitamin K administration. For each VKD case, two gestational age- and sex-matched controls were selected. Maternal background characteristics were compared, and multivariate logistic regression was performed to identify independent risk factors for neonatal VKD.

Among 64 neonates with VKD and 128 controls, maternal prepregnancy obesity (body mass index ≥25) was significantly more common in the VKD group. Multivariate analysis identified prepregnancy obesity as an independent risk factor for neonatal VKD (odds ratio 3.97, P < 0.001). Additionally, maternal prepregnancy BMI was positively correlated with neonatal PIVKA-II levels at birth (r = 0.285, P < 0.0001).

Maternal prepregnancy obesity is independently associated with an increased risk of VKD in neonates at birth. These findings suggest that targeted evaluation and vitamin K management strategies are warranted in pregnancies complicated by maternal obesity.