@article{3092007,
    title = "A prospective study of pregravid oral contraceptive use in relation to
fetal growth",
    author = "Mucci, LA and Lagiou, P and Hsieh, CC and Tamimi, R and Hellerstein, S and and Vatten, L and Adami, HO and Cnattingius, S and Trichopoulos, D",
    journal = "BJOG: An International Journal of Obstetrics and Gynaecology",
    year = "2004",
    volume = "111",
    number = "9",
    pages = "989-995",
    publisher = "Wiley-Blackwell Publishing Ltd",
    issn = "1470-0328, 1471-0528",
    doi = "10.1111/j.1471-0528.2004.00232.x",
    abstract = "Objective Because oral contraceptives are so widely used, any health
consequences may have substantial public health implications. Whether
pregravid oral contraceptives could affect subsequent pregnancies has
not been adequately studied. The study objectives were to examine
whether pregravid oral contraceptive use affects fetal growth and
pregnancy hormone levels.
Design A prospective study of pregnant women followed through pregnancy.
Setting A major teaching hospital in Boston, USA.
Population Two hundred and sixty Caucasian pregnant women, with a mean
age of 31, and a parity of no more than two. Seventy-nine percent of the
women were pregravid oral contraceptive users.
Methods Exposure and covariate data were collected through structured
questionnaires. Blood was drawn for hormonal analysis during the 16th
and 27th gestational week. Information on pregravid oral contraceptive
use included duration and recency of use, and oral contraceptive
formulation. Multivariate regression models were used to examine the
effect of pregravid oral contraceptive use on birth outcomes and the
studied pregnancy hormones.
Main outcome measures Birthweight, placental weight, gestational age,
pregnancy hormone levels of oestriol and progesterone at 16th and 27th
gestational week.
Results Adjusting for confounders, pregravid oral contraceptive use
increased birthweight (mean difference +207.3 g, 95% CI = +77.6 to
+337.1) and placental weight (mean difference = +64.9 g, 95% CI = +13.0
to+116.9) compared with never use. Women with prior oral contraceptive
use had higher levels of serum progesterone (P = 0.002) and oestriol (P
= 0.12) at the 27th gestational week measurement. The effect on
birthweight, placental weight and hormones was stronger among those
using oral contraceptives in the previous year and those using a high
progestin/high oestrogen potency preparation.
Conclusions Pregravid oral contraceptive use is positively associated
with fetal growth, and this effect may be mediated through oestriol and
progesterone."
}