Sunshine, Fertility and Racial Disparities

48 Pages Posted: 4 Mar 2018

See all articles by Karen Smith Conway

Karen Smith Conway

University of New Hampshire

Jennifer Trudeau

Sacred Heart University

Date Written: February 22, 2018


This research investigates the effect of sun exposure on fertility, with a special focus on how its effects and consequences for birth outcomes may differ by race. Sun exposure is a key mechanism for obtaining Vitamin D, but this process is inhibited by skin pigmentation. Vitamin D has been linked to male and female fertility and risk of miscarriage, and Vitamin D deficiency is more prevalent among blacks than whites. Using 1989-2004 individual births data from the Natality Detail Files, county-level, monthly conceptions are estimated as a function of monthly solar insolation, temperature and humidity, as well as month, time and location fixed effects and controls. Insolation has positive, statistically significant effects on fertility for both nonHispanic blacks and whites, but the effects are stronger and the pattern of effect different for black mothers than white mothers. Estimates from the main model suggest that a 1 kwh increase in average daily insolation in the conception month – approximately the difference in sunshine experienced in the typical September vs. October – increases nonHispanic black conceptions by 1% and nonHispanic white conceptions by 0.6%. Models that allow for more complicated timing of insolation’s effect further suggest that insolation pushes black (white) conceptions into the unfavorable (favorable) season of birth. These estimated effects suggest that insolation – and the implied Vitamin D deficiency underlying its effect – helps explain why black conceptions are more likely to display a seasonal pattern that is disadvantageous to birth outcomes.

Keywords: Fertility, sunshine, solar insolation, temperature, racial differences, season of conception/birth

JEL Classification: I1, Q5, J13

Suggested Citation

Conway, Karen Smith and Trudeau, Jennifer, Sunshine, Fertility and Racial Disparities (February 22, 2018). Available at SSRN: or

Karen Smith Conway (Contact Author)

University of New Hampshire ( email )

15 College Road
Durham, NH 03824
United States

Jennifer Trudeau

Sacred Heart University ( email )

5151 Park Avenue
Fairfield, CT 06825
United States

Do you have a job opening that you would like to promote on SSRN?

Paper statistics

Abstract Views
PlumX Metrics