Phthalate has been widely used as a type of plasticiser in various consuming products in daily life. Recent studies have suggested that prenatal
phthalate exposure may have adverse effects on fetal development. We aimed to identify the effects of in utero
phthalate exposure on
birth weight (BW). We evaluated a birth cohort comprising 3474 pregnant women and their single infants; 3103, 2975 and 2838 urine samples were collected in the first, second and third trimesters, respectively.
Phthalate metabolites included
monomethyl phthalate (
MMP),
monoethyl phthalate (MEP),
mono-n-butyl phthalate (MBP), monobenzyl
phthalate (MBzP), mono-(2-ethylhexyl)
phthalate (
MEHP), mono-(2-ethyl-5-oxohexyl)
phthalate (MEHHP), and mono-(2-ethyl-5-hydroxylhexyl)
phthalate (MEOHP), which were analysed in the urine by using high performance liquid chromatography-tandem mass spectrometry. Mixed linear model was used in the statistical analysis. Generally,
MMP and MEP exposure during pregnancy was associated with decreased
birth weight of infants (
MMP, β=-12.192, p=0.009; MEP, β=-11.876, p=0.014). Hierarchical analysis found that
MMP and MEOHP exposure was associated with decreased infants'
birth weight only in low birth weight groups (
MMP, β=-42.538, p=0.005; MEOHP, β=-63.224, p=0.008);
MEHP and MEHHP exposure was associated with decreased infants'
birth weight in both low birth weight group (
MEHP, β=-42.348, p=0.035; MEHHP, β=-50.485, p=0.006) and high
birth weight group (
MEHP, β=-16.580, p=0.034; MEHHP, β=-18.009, p=0.040), MBP and
MEHP exposure were associated with increased infants'
birth weight in male NBW group (MBP, β=10.438, p=0.039;
MEHP, β=13.223, p=0.017). Moreover, the effect has sex difference. The reduction of
birth weight associated with
MEHP and MEOHP exposure was stronger in male infants, while
MMP and MEP exposure was more significant in female infants.