Context: The majority of patients with hypoparathyroidism (HypoPT) are women. It is not known whether the presence of hypoparathyroidism influences the pregnancy outcomes. Sweden has excellent conditions for research in this area, with high-quality population-based registers covering essentially all inpatient care and birth records. In this study, data were linked from the Swedish National Patient Register and Swedish Medical Birth Register to examine the potential influence of maternal hypoPT on the number of childbirths and various pregnancy outcomes.
Results: There was no significant difference in mean age at delivery for women with HypoPT (32 (SD, 5.2)) years and controls (32.5 (5.0)). There were significantly more women with HypoPT who smoked at baseline (p= 0.007) and within 3 months of pregnancy (p=0.022) compared to controls. Significantly more women with HypoPT had part time work or were not working during pregnancy compared to controls (p = 0.002). The mean number of infants per woman was 0.30 (SD, 0.62) in the HypoPT group and 0.33 (SD, 0.60) in the control group (p=0.644). Compared with the control group, the risk of elective cesarean section was higher in the HypoPT group (p=0.002). However, there was no difference in the proportion of women undergoing an acute cesarean section between cases and controls (p=0.754). The mean pregnancy duration in women with HypoPT was 38.87 (2.11) weeks compared to 39.23 (2.04) weeks for the controls (p= 0.001). Infants born to mothers with HypoPT were significantly shorter (p=0.016), but no difference was seen in weight or head circumference compared to infants born to controls. No difference was observed in prevalence of small- or large-for gestational age compared to controls. There were no differences between groups with respect to infant sex or Apgar scores at 1, 5 and 10 min, congenital malformations or stillbirth. There was furthermore no difference in pain medication use by mothers during delivery between the groups (p=0,733).
Conclusion: The majority of women with HypoPT had normal pregnancy outcomes, and the overall risks must be considered to be low. Still, our findings are of importance for antenatal counseling in women with HypoPT as their risk for elective cesarean section was significantly higher compared with controls. Their children were shorter and the higher rate of smoking among HypoPT women may be an additional risk factor.