Women with chronic hypoparathyroidism generally had normal pregnancy outcomes with low risks, but rates of induced labor were higher. This is according to research results published in The Journal of Clinical Endocrinology and Metabolism.

Most patients living with chronic hypoparathyroidism are women. During pregnancy, close monitoring of chronic hypoparathyroidism is important because both hypo- and hypercalcemia can negatively affect the fetus. Management of chronic hypoparathyroidism during pregnancy is challenging, however, and relevant data on the topic is lacking; published works primarily take the form of case reports or small case series.

Accessing the high-quality, population-based registers available in Sweden, researchers used linked data to evaluate the potential influence of maternal chronic hyperparathyroidism on pregnancy outcomes.


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Researchers identified 1520 women with chronic hypoparathyroidism and 15,200 control patients. In the chronic hypoparathyroidism group, 6.4% of women gave birth to 139 singleton infants following diagnosis. In the control group, 6.8% of women gave birth to 1577 singleton infants. All births were recorded between 1997 and 2017.

The mean age of women in the database when first recorded with a chronic hypoparathyroidism diagnosis was 26.9±6.5 years. Within the cohort, 76.4% and 23.6% of women had postsurgical and nonsurgical chronic hypoparathyroidism, respectively.

Maternal weight, age at delivery, smoking and oral tobacco use, family and working status, and calendar year of delivery were not different between groups. There were, however, more pregnancies in the chronic hypoparathyroidism group in cases where the mother received thyroxine vs control patients (64% vs 5.1%).

The total number of births did not differ significantly between the 2 groups.

Mean gestational age at delivery was “slightly albeit significantly shorter” in women in the chronic hypoparathyroidism group (38.7±2.4 vs 39.2±2.1 weeks). After adjustments were made for maternal diabetes, chronic kidney disease, and preeclampsia, this difference was not significant.

Chronic hypoparathyroidism was also associated with a 1.82-fold increased risk of induction of labor after adjustments were made for diabetes, chronic kidney disease, maternal age at delivery, and calendar year of delivery (odds ratio [OR], 1.82; 95% CI, 1.13-2.94). The condition remained significantly associated with a 1.79-fold increased risk of labor induction, independent of both preeclampsia and gestational age.

When investigators stratified labor induction by gestational age, it was only significantly increased in women with a gestational length of 40 to 41 weeks plus 6 days. Controlling for thyroxine exposure found that the effect of chronic hypoparathyroidism on the risk of labor induction was not significant (OR, 1.58; 95% CI, 0.95-2.61). No between-group differences in the proportion of cesarean delivery or postpartum hemorrhage were noted.

Mean birth weight was significantly lower in neonates of women with chronic hypoparathyroidism vs control patients (3329±620 g vs 3506±624 g). The association between maternal chronic hypoparathyroidism and low birth weight remained significant even after adjusting for maternal diabetes, chronic kidney disease, maternal age at delivery, and calendar year of delivery (OR, -188 g; 95% CI, -312.2 g to -63.8 g).

Chronic hypoparathyroidism was also significantly associated with a mean 89.68-g reduction in birth weight after researchers also controlled for preeclampsia and gestational weight. Low birth weight was also significant after controlling for thyroxine exposure during pregnancy; however, no difference was noted in terms of incidence of small for gestational age infants or for infant length or head circumference.

When comparing surgical and nonsurgical groups, there was no significant difference in pregnancy outcomes. However, the researchers noted that this could be due to small patient numbers in each group.  

Study limitations include potential exclusion of some women with chronic hypoparathyroidism due to the strict inclusion criteria and a lack of biochemical data, pharmacology treatment dosage data, and information on dietary intake of calcium during pregnancy. Researchers also lacked genetic data on patients with nonsurgical chronic hypoparathyroidism, and they did they have access to long-term outcomes.

“This is the first population-based epidemiological study of pregnancy outcomes in women with chronic [hypoparathyroidism],” the researchers wrote. “The majority of women had normal pregnancy and delivery outcomes with low risk of adverse perinatal outcome.”

“It is however important to coordinate the prenatal care of women with chronic [hypoparathyroidism] between the treating endocrinologist and the maternal-fetal medicine specialist to ensure optimal maternal and neonatal outcomes,” they concluded.

Disclosure: This clinical trial was supported by Shire/Takeda and the Novo Nordisk Foundation. Please see the original reference for a full list of authors’ disclosures.

Reference

Björnsdottir S, Clarke B, Mäkitie O, et al. Women with chronic hypoparathyroidism have low risk of adverse pregnancy outcomes. J Clin Endocrinol Metab. Published online July 8, 2021. doi:10.1210/clinem/dgab503