Maternal hypothyroidism and future pediatric neurological morbidity of the offspring.

BACKGROUND

Maternal hypothyroidism in pregnancy has been associated with neurocognitive impairment in exposed children, ranging from psychomotor-developmental delay to lower IQ scores.

OBJECTIVE

To investigate the long-term neurological morbidity of children to hypothyroid mothers during pregnancy.

STUDY

DESIGN

A population-based cohort study was performed including all deliveries occurring in a period of 20 years at a tertiary medical center. We excluded multiple pregnancies, fetuses with congenital malformations, perinatal mortality cases and women lacking prenatal care from the study. Neurological-related hospitalizations of children (up to 18 years) were evaluated using neurological morbidities that were predefined by ICD-9 codes. Kaplan-Meier survival curve was used to compare cumulative hospitalization rate in exposed and unexposed children. A Cox regression model was used to control for confounders.

RESULTS

During the study period, 217,910 deliveries met the inclusion criteria. Of them, 1.1% (n = 2403) were in mothers with known hypothyroidism during pregnancy. The Kaplan-Meier survival curve demonstrated a significantly higher cumulative incidence of neurological-related hospitalizations in the hypothyroidism group (log rank p = 0.007). Total hospitalization rate per person years was significantly higher in the maternal hypothyroidism group (5.5 vs. 3.1, HR =1.37, 95% CI 1.10-1.73, p = 0.007). The Cox regression model controlled for various possible confounders including maternal age, maternal obesity, birth weight, preterm birth, maternal diabetes, hypertensive disorders, induction of labor and mode of delivery, found maternal hypothyroidism to be independently associated with pediatric neurological morbidity in these children (adjusted HR =1.33, 95% CI 1.05-1.68, p = 0.01).

CONCLUSION

Maternal hypothyroidism in pregnancy is independently associated with long-term pediatric neurological morbidity of the offspring.