Ba. Kolb et Rj. Paulson, THE LUTEAL-PHASE OF CYCLES UTILIZING CONTROLLED OVARIAN HYPERSTIMULATION AND THE POSSIBLE IMPACT OF THIS HYPERSTIMULATION ON EMBRYO IMPLANTATION, American journal of obstetrics and gynecology, 176(6), 1997, pp. 1262-1267
OBJECTIVE: Our purpose was to evaluate the early luteal phase of assis
ted reproductive cycles utilizing controlled ovarian hyperstimulation
and to compare these results with those obtained in unstimulated cycle
s. STUDY DESIGN: We undertook a descriptive study analyzing luteal pha
se serum progesterone levels, endometrial histologic features, and end
ometrial surface ultrastructure by scanning electron microscopy of cyc
les utilizing controlled ovarian hyperstimulation. Study samples were
obtained from 7 oocyte donors undergoing controlled ovarian hyperstimu
lation for the purpose of follicle aspiration in oocyte donation. Cont
rol (unstimulated) serum progesterone samples were obtained from 19 pa
tients undergoing in vitro fertilization in unstimulated cycles. Prosp
ective recipients of oocyte donation (n = 20) undergoing mock cycles o
f exogenous estradiol and progesterone acted as controls for the endom
etrial biopsies. RESULTS: Serum progesterone levels on the day of huma
n chorionic gonadotropin administration were twofold higher in the stu
dy group than in the unstimulated group (1.1 +/- 0.6 vs 0.5 +/- 0.2 ng
/ml, mean +/- SD, p < 0.01). On the day of follicle aspiration, proges
terone levels were much higher in the study group (8.5 +/- 2.2 vs 0.5
+/- 0.1 ng/ml, p < 0.001). Histologic dating of endometrial biopsies r
evealed that the study group was advanced by nearly 2 days as compared
with the group having artificial cycles. Pinopods, ultrastructural ma
rkers of the implantation window, were present in only one of seven st
udy cycles as compared with all of the four artificial cycles. CONCLUS
IONS: The early luteal phase of cycles undergoing controlled ovarian h
yperstimulation is characterized by markedly elevated serum progestero
ne levels during the periovulatory period, advanced endometrial histol
ogic features, and an absence of endometrial pinopods at the time of e
mbryo implantation. We speculate that these high levels of progesteron
e in the early luteal phase cause premature endometrial luteinization
and a premature appearance of the implantation window, thus providing
an explanation for the observed decrease in endometrial receptivity.