A STUDY OF MATERNAL AGE AND THYROID STATUS AND ITS ASSOCIATION WITH NEONATAL CONGENITAL HYPOTHYROIDISM

Abstract

The prevalence of congenital hypothyroidism is high in India at 5.7 per 10,000 infants and an incidence
rate of 1 in 244 in Kerala state. Neonatal mass screening programs have been largely successful in
early diagnosis of congenital hypothyroidism. Both, very young and advanced maternal age are
considered at risk for adverse pregnancy outcomes which in turn may be a factor for development of
congenital hypothyroidism in neonates. The studies related to the role of maternal age as a risk factor
for development of congenital hypothyroidism are minimal. Not much studies are available which
analyse the association of adequately treated maternal hypothyroidism on the neonatal thyroid
dysgenesis and other causes of neonatal congenital hypothyroidism. The study collected data about the
age and thyroid status of 120 mothers of neonates in which n=60 cases were Mothers of the neonates
with congenital hypothyroidism (TSH > 15.2 µIU/mL) and n=60 controls mothers of euthyroid healthy
neonates (TSH ≤ 15.2 µIU/mL). Data collected regarding the maternal thyroid status was evaluated in
the antenatal period during first trimester and neonatal thyroid status was evaluated at birth from cord
blood. All the mothers included in the study with hypothyroidism (both cases and controls) were either
already on treatment or were treated appropriately during pregnancy. The mean maternal age in cases
(n=60) was 34.8± 5.7 years while that in control (n=60) was 25.43± 4.3 years. There is a high
statistically significant (p<0.0001) increase in maternal age in cases compared to controls. The odds of
being ≥35 years were higher in mothers of neonates with congenital hypothyroidism as compared to
mothers of normal children with Odds ratio of 5.06; and highly significant P value 0.0001. The odds of
mothers of neonates with congenital hypothyroidism having hypothyroidism, compared mothers of
euthyroid neonates having hypothyroidism is not statistically significant with Odds ratio of 3.14; with P
value 0.06. The risks of acquiring congenital hypothyroidism in neonates increase with advanced
maternal age. Neonatal TSH levels are dynamic and are affected by several factors including maternal
hypothyroidism. Pre-conceptional consultation and evaluation of thyroid status as well as first trimester
universal screening and adequate treatment of maternal hypothyroidism may play an effective role in
decreasing the incidence of neonatal congenital hypothyroidism, especially in high risk pregnancies
due to advanced maternal age.