PURPOSE: In Scandinavia, delivery of a first-born @entity5461 elevates the risk of @entity3152 and intrauterine growth restriction of the next-born @entity1 . External validity of these results remains unclear. We test this hypothesis for @entity3152 and growth restriction using the linked California birth cohort file. We examined the hypothesis separately by race and/or ethnicity. METHODS: We retrieved data on 2,852,976 births to 1,426,488 mothers with at least two live births. Our within-mother tests applied Cox proportional hazards ( @entity3152 , defined as less than 37  weeks gestation) and linear regression models (birth weight for gestational age percentiles). RESULTS: For non-Hispanic whites, Hispanics, Asians, and American Indian and/or Alaska Natives, analyses indicate heightened risk of @entity3152 and growth restriction after a first-born male. The race-specific hazard ratios for @entity3152 range from 1.07 to 1.18. Regression coefficients for birth weight for gestational age percentile range from  -0.73 to  -1.49. The 95% confidence intervals for all these estimates do not contain the null. By contrast, we could not reject the null for @entity7864 . CONCLUSIONS: Whereas @entity7452 generally support those from Scandinavia, the null results among @entity7864 suggest that we do not detect adverse outcomes after a first-born male in all racial and/or ethnic groups.

Heightened risk of preterm birth and growth restriction after a first-born XXXX .

@entity5461 :: ('6651', 'Gene') :: ['son'] @entity1 :: ('9606', 'Species') :: ['infant'] @entity7864 :: ('MESH:D055008', 'Disease') :: ['non-Hispanic black mothers'] @entity3152 :: ('MESH:D007752', 'Disease') :: ['preterm delivery'] @entity7452 :: ('MESH:D004670', 'Disease') :: ['California findings']
@entity5461 :: (6651,Gene) :: ['son']
