Skip to Main Content
Table 3

Comparison of results' magnitude across a selection of articles using LBW as an outcome

StudyLocationSampleHeat (°C)SESTrimesterStatisticResults
P(LBW)
This Study: Table 1, Table S2 (online appendix) 50 provincial Spanish capitals 4,314,381 singletons >32° Parental SES assessed with ISCO, which is coded using ISEI and categorized as high, medium, and lowa First/second One-day increase ↑ 0.029 PP base
↑ 0.085 PP low
↓–0.001 PP high 
Chen et al. (2020: tables 2 and 7) Rural areas in 31 Chinese provinces 637,033 singletons >28° Maternal education (low ≤ middle school) Third One-day increase 
↑ 0.035 PP base
↑ 0.031 PP low
↓–0.007 PP high 
Liu et al. (2022: table A6) District in the center city of Guangzhou, China 67,108 >34.23° (top 1%) Maternal education (low ≤ high school) — 1% of a pregnancy (2.7 days), here transformed to one-day increase ↑ 0.15 PP base ↑ 0.19 PP low ↑ 0.037 PP high 
Ngo and Horton (2016: table A1) New York City, USA 514,104 >29.44° — Second One-day increase 
↑0.046 PP base
(LBW by SES not studied) 
Hajdu and Hajdu (2021: figure 2) Hungary 1,532,661 singletons >25° Maternal education (low ≤ secondary school) Second/third One-day increase 
Not significant, ≈ 0.01 PP (no SES differences) 
Cho (2020: table 9) South Korea 2,300,000 ≥32° — First/second One-day increase Not significant, ≈ 0.036 PP highest estimate 
StudyLocationSampleHeat (°C)SESTrimesterStatisticResults
P(LBW)
This Study: Table 1, Table S2 (online appendix) 50 provincial Spanish capitals 4,314,381 singletons >32° Parental SES assessed with ISCO, which is coded using ISEI and categorized as high, medium, and lowa First/second One-day increase ↑ 0.029 PP base
↑ 0.085 PP low
↓–0.001 PP high 
Chen et al. (2020: tables 2 and 7) Rural areas in 31 Chinese provinces 637,033 singletons >28° Maternal education (low ≤ middle school) Third One-day increase 
↑ 0.035 PP base
↑ 0.031 PP low
↓–0.007 PP high 
Liu et al. (2022: table A6) District in the center city of Guangzhou, China 67,108 >34.23° (top 1%) Maternal education (low ≤ high school) — 1% of a pregnancy (2.7 days), here transformed to one-day increase ↑ 0.15 PP base ↑ 0.19 PP low ↑ 0.037 PP high 
Ngo and Horton (2016: table A1) New York City, USA 514,104 >29.44° — Second One-day increase 
↑0.046 PP base
(LBW by SES not studied) 
Hajdu and Hajdu (2021: figure 2) Hungary 1,532,661 singletons >25° Maternal education (low ≤ secondary school) Second/third One-day increase 
Not significant, ≈ 0.01 PP (no SES differences) 
Cho (2020: table 9) South Korea 2,300,000 ≥32° — First/second One-day increase Not significant, ≈ 0.036 PP highest estimate 

Notes: The table summarizes the literature on the effect of heat on LBW. We select baseline estimates and, where found, also differences by SES, taking the largest estimate. We include only research with comparable temperature bins or similar estimations of the effect of heat on birth outcomes. PP = percentage points; base = baseline; low = low SES; and high = high SES.

a

For a subsample, we also report an estimate of the effect of temperatures above 32°C on the birth outcome, with SES defined as maternal education. We define low educated as having less than a university degree, and we find an increase of 0.122 percentage points with heat experienced in the second trimester (Table S6, online appendix).

Close Modal

or Create an Account

Close Modal
Close Modal