Estimated effect of extreme heat (>32°C/>89.6°F) on birth outcomes, by SES and trimester of pregnancy. PTB = preterm birth. LBW = low birth weight. VLBW = very low birth weight. Estimates are obtained from Table S2 (online appendix), which also displays full estimates for other temperature bins. Coefficients, scaled by 100 to enhance readability, can be interpreted as percentage-point changes in the specific birth outcome. Each model includes fixed effects for province × year of conception, the province-specific polynomial quadratic in the century-month of conception, and the month of conception. Demographic control variables include the mother's marital status, the mother's age, age squared, whether the child is the firstborn, and the mother's ethnic origin. Contextual controls include population density, the female employment rate, the logarithm of the provincial GDP, the provincial cohort–specific share of women with a tertiary degree, and vegetation's leaf area index. Climatic controls include relative humidity, solar radiation, wind speed, and average precipitation. Whiskers represent 95% confidence intervals.