Extreme differences in daily photoperiod during pregnancy may be related to risk for lifetime depression in offspring, with a heightened risk during the second trimester of pregnancy, according to a study recently published in the Journal of Psychiatric Research.

Researchers studied 160,723 participants from the longitudinal Nurse’s Health Study (NHS) of 1976 and a newer study in 1989 (NHS II) to analyze photoperiod during pregnancy and lifetime depression in offspring. The Institutional Review Board of Brigham and Women’s Hospital approved the studies, and consent was implied when participants returned updated questionnaires.

Based on collected information, researchers estimated day length during the presumed pregnancy period and suicide or depression rates among offspring in correlation. Total photoperiod, defined as the total number of daylight hours, during pregnancy was borderline significantly related to clinician-diagnosed depression. However, greater differences between minimum and maximum photoperiod during pregnancy were associated with lower odds of depression, specifically in the second trimester of pregnancy (multivariable-adjusted P trends =.02, <.0001, and 0.45 across the 3 trimesters, respectively).

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In addition, researchers observed that women born in northern latitudes had 7% lower odds of lifetime depression compared with women born in middle latitudes, whereas women born in the southern latitudes had 15% greater odds of depression.

Researchers concluded that, “in this study, extreme differences in daily photoperiod, but not total photoperiod, during maternal pregnancy were related to risk [for] lifetime depression in the participant-offspring.” Researchers suggested that photoperiod results could lead to light-related interventions during pregnancy.


Devore EE, Chang SC, Okereke OI, McMahon DG, Schernhammer ES. Photoperiod during maternal pregnancy and lifetime depression in offspring. J Psychiatr Res. 2018; 104:169-175. doi: 10.1016/j.jpsychires.2018.08.004

This article originally appeared on Psychiatry Advisor