FRI477 The Effect Of Gestational Selective Serotonin Reuptake Inhibitor (SSRI) Treatment On Newborn Thyroid Screen

Disclosure: A. Brener: None. O. Raviv: None. E. Cohen-Sela: None. M. Yackobovitch-Gavan: None. S. Almashanu: None. R. Marom: None. L. Hiersch: None. Y. Lebenthal: None. Background: Clinical depression treated by selective serotonin reuptake inhibitors (SSRIs) has become relatively common in women of childbearing age. The effect of gestational exposure to SSRIs on the newborn’s hypothalamic-pituitary-thyroid postnatal adaptation has not yet been determined. We aimed to investigate the characteristics of the mother–infant dyad of term infants of mothers treated with SSRIs for depression during pregnancy. Methods: This observational study included mother-infant dyads of infants delivered at term in a single tertiary medical center between 2011 and 2021. Data on maternal, pregnancy, delivery, and perinatal characteristics of the mother-infant dyads were retrieved from the hospital’s electronic database. The clinical data were linked with the newborn thyroid screening results of total thyroxin (TT4) obtained at 48-72 hours since delivery. Excluded from analysis were mothers with other chronic medical conditions and newborns with genetic syndromes. Primary outcome measures were newborn TT4 levels and fetal growth as expressed by neonatal birthweight z-scores (WHO charts). Results: SSRI anti-depression treatment during gestation was reported in 2577 (2.4%) out of 106,173 infant-mother dyads. Mothers treated with SSRIs were older (35.0±4.8 vs 32.6±4.8 years, p<0.001), had a higher pre-pregnancy body mass index (23.4±4.5 vs 22.7±4.1, p<0.001) and a similar mean weight gain of 13 kg during pregnancy. Elective and emergent cesarean deliveries were more common among SSRI-treated mothers (14.8% vs 11.1% and 16.5% vs 8.6%, respectively, p<0.001). Infants of those mothers were born earlier (gestational age [GA] 38.7±1.9 vs 39.5±11.5 weeks, p<0.001), had lower birthweight z-scores (-0.48±1.24 vs -0.04±0.92, p<0.001) and lower TT4 levels (14.7±3.9 vs 15.0±3.7, p=0.001). A multivariate linear regression model revealed that sex, GA and birthweight z-score were highly significant contributors to TT4 levels (p<0.001 for all), while SSRI treatment during pregnancy was not (p=0.497). Conclusions: Our findings suggest that anti-depressant use of SSRIs during pregnancy does not have a direct effect on the postnatal adaptation of the hypothalamic-pituitary-thyroidal axis. However, differences in fetal growth and in characteristics of delivery may determine newborn thyroid function. Presentation: Friday, June 16, 2023