Short stature, smoking habits and birth outcome in international adoptees in Sweden.

OBJECTIVE: To investigate short stature and smoking habits as risk factors for birth outcome in international adoptees in comparison with non-adopted mothers.

DESIGN: Prospective cohort study.

SETTING: Nationwide study in Sweden.

POPULATION: Two study groups were identified from mothers who were born 1968-1979 and gave birth during 1982-2001-3,610 mother-child dyads with a mother adopted from a non-European country and 336,992 mother-child dyads with a mother born in Sweden.

METHOD: Register study.

OUTCOME MEASURES: Pre-eclampsia, instrumental delivery, preterm delivery, small for gestational age (SGA), Apgar score, cephalhematoma and perinatal mortality and birth weight.

RESULTS: Short stature and smoking were more common in international adoptees compared with non-adopted, odds ratios (ORs) 29.07 (95% C.I.: 25.29-33.42) and 1.39 (1.27-1.52), respectively. International adoptees had a slightly increased risk for instrumental delivery (OR: 1.42; 1.32-1.54) and preterm delivery (<37 weeks) (OR: 1.39; 1.24-1.56) and there was a slightly increased risk for SGA (OR: 1.24; 1.01-1.52) in their offspring. However, when we adjusted for maternal height, preterm delivery was the only outcome that remained statistically significant. Adjustment for smoking habits had marginal effects on all outcomes.

CONCLUSION: The short stature of international adoptees increased their risk for delivery and birth complications in a predictable manner, but otherwise outcomes were very similar to the general population. No special obstetric monitoring is indicated by adoption status in itself.