@article{3044121,
    title = "COMPARISON OF MATERNAL SERUM ESTRADIOL AND PROGESTERONE LEVELS IN
PREGNANCIES AFTER INDUCED AND SPONTANEOUS OVULATION",
    author = "HASSIAKOS, D and MANTZAVINOS, T and KALOMIRIS, K and ZOURLAS, PA",
    journal = "Archives of Gynecology and Obstetrics",
    year = "1991",
    volume = "248",
    number = "3",
    pages = "145-150",
    publisher = "Springer-Verlag",
    issn = "0932-0067, 1432-0711",
    doi = "10.1007/BF02390092",
    keywords = "OVULATION INDUCTION; PREGNANCY; ESTRADIOL; PROGESTERONE",
    abstract = "Maternal serum estradiol and progesterone levels during the early 6th to
15th weeks of gestation, were measured by radioimmunoassay in 140
pregnancies following induction of ovulation with gonadotropins or
clomiphene citrate.  The levels were compared with those observed in 79
spontaneous pregnancies.  Significantly higher levels were observed in
gonadotropin and clomiphene citrate induced pregnancies (both P values <
0.001) between the 6th to 9th week of gestation as compared to
spontaneous pregnancies.  Steroid levels were similar in the two groups
from the 9th week onwards.  No statistically significant differences in
steroid hormone values were observed in aborted and successful
pregnancies within each group studied.  We conclude that ovulation
induction is associated with higher estradiol and progesterone levels
until placental steroidogenesis starts."
}