Inhibin and relaxin concentrations in early singleton, multiple, and failing pregnancy: relationship to gonadotropin and steroid profiles.
OBJECTIVE
To examine the inter-relationships between inhibin, relaxin, steroid concentrations, estradiol (E2), progesterone (P), and gonadotropins in early pregnancy.


METHODS
Hormone concentrations in plasma were measured during the luteal phase of subjects who became pregnant (n = 58) or failed to become pregnant (n = 47) after ovarian hyperstimulation for in vitro fertilization-gamete intrafallopian transfer (IVF-GIFT) (group 1). A further group of subjects became pregnant (n = 7) or failed to become pregnant (n = 8) during endocrinology tracking of a natural cycle (group 2). Blood was obtained every 3 days in the luteal phase from day 5 in group I (day 0 was oocyte recovery) and from day 0 (first increase in luteinizing hormone [LH]) in group II.


RESULTS
Progesterone and E2 were increased over nonpregnant values by day 11 (P) and day 16 (E2) in group I and by day 11 (E2 and P) in group II. Inhibin and relaxin concentrations were significantly increased by day 16 in group I (often by day 11) and by day 14 in group II pregnancy subjects. A direct relationship existed between inhibin, P, relaxin, and human chorionic gonadotropin (hCG). Subjects who had twin pregnancies demonstrated higher concentrations of all hormones and often exhibited increases earlier (by day 11 in group I) than singleton pregnancy subjects. Pregnancies that ended in miscarriages tended to have lower concentrations of P and inhibin. None of the hormones reliably discriminated between the clinical conditions of blighted ovum and of spontaneous abortion, and the predictive value of any hormone measured for miscarriage was not high.


CONCLUSIONS
The trend of inhibin and relaxin concentrations closely parallels rises in P during early pregnancy. Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels are suppressed very early in pregnancy. The suppression of LH and FSH in hyperstimulated cycles is more governed by E2 than inhibin in stimulated cycles. Some subjects destined to miscarry exhibit abnormal endocrine changes very early in the luteal phase.
Norman
R J
RJ
Department of Obstetrics and Gynaecology, University of Adelaide, Woodville, South Australia.
McLoughlin
J W
JW
Borthwick
G M
GM
Yohkaichiya
T
T
Matthews
C D
CD
MacLennan
A H
AH
de Kretser
D M
DM
D000022:Abortion, Spontaneous / Q000097:blood; D006063:Chorionic Gonadotropin / Q000097:blood; D005260:Female; D012739:Gonadal Steroid Hormones / Q000097:blood*; D006065:Gonadotropins, Pituitary / Q000097:blood*; D006801:Humans; D007265:Inhibins / Q000097:blood*; D008597:Menstrual Cycle / Q000097:blood; D009994:Osmolar Concentration; D011247:Pregnancy / Q000097:blood*; D011272:Pregnancy, Multiple / Q000097:blood*; D012065:Relaxin / Q000097:blood*; D013997:Time Factors
D006063:Chorionic Gonadotropin; D012739:Gonadal Steroid Hormones; D006065:Gonadotropins, Pituitary; D007265:Inhibins; D012065:Relaxin