New-onset hypertension in late pregnancy and fetal growth: different associations between singletons and twins.
OBJECTIVE
To compare the effects of new-onset hypertension (NOH) in late pregnancy on fetal growth in singletons and twins.


METHODS
A retrospective cohort study was conducted to evaluate the effect of NOH on fetal growth in 17, 720, 900 singletons and 463, 104 twins born in the United States between 1995 and 2000.


RESULTS
NOH was associated with lower mean birth weight in both preterm and term singletons. Increased risk of low birth weight and decreased risk of high birth weight was associated with NOH in preterm and term singletons. NOH was associated with increased risk for small-for-gestational-age (SGA) births and decreased risk for large-for-gestational-age (LGA) births in preterm singletons, whereas it was associated with increased risk of both SGA and LGA births in term singletons. NOH was associated with higher mean birth weight in early preterm twins, and lower mean birth weight in term twins. Decreased risk for low birth weight was found in the NOH group among early preterm twins, and increased risk for low birth weight in term twins. NOH was associated with increased risk of SGA births and decreased risk for large-for-gestational-age (LGA) births in early preterm twins, while increased risk of SGA births in term twins.


CONCLUSIONS
NOH is associated with slower fetal growth in singletons delivered at different gestational ages, but the effect varies in twins depending on gestational age at delivery with faster growth in early preterm twins.
Chen
Xi-Kuan
XK
OMNI Research Group, Clinical Epidemiology Program, Ottawa Health Research Institute, University of Ottawa, Ottawa, Ontario, Canada.
Wen
Shi Wu
SW
Smith
Graeme N
GN
Yang
Qiuying
Q
Walker
Mark C
MC
D000328:Adult; D015331:Cohort Studies; D005260:Female; D047109:Fetal Development / Q000502:physiology*; D005865:Gestational Age; D006801:Humans; D046110:Hypertension, Pregnancy-Induced / Q000503:physiopathology*; D007231:Infant, Newborn / Q000254:growth & development*; D007234:Infant, Premature; D011247:Pregnancy; D047928:Premature Birth / Q000503:physiopathology*; D012189:Retrospective Studies; D014427:Twins / Q000502:physiology*