Objective: Polymorphic variants of the human progesterone receptor gene have been described, but their potential influence on in vitro fertilization outcome have not been studied.
Study design: DNA was available from 317 women (cases) who had >or=2 embryo transfers without a clinical pregnancy and from 288 women (control subjects) who became pregnant after 1 in vitro fertilization attempt. With protocols that were specific for H770H (C/T genotype) and +331G/A polymorphism, amplification of polymorphism fragments, digestion with restriction enzymes, and gel visualization were performed.
Results: Allele frequencies for the 2 variants were 15.5% for H770H T and 4.1% for +331A in cases and 17.9% and 3.6% in control subjects, respectively. Both polymorphisms were rare among non-white subjects. Possession of a H770H T allele was associated with a decreased risk for implantation failure, which was nonsignificant overall but significant in women aged <35 years (adjusted relative risk, 0.52 [95% CI, 0.28, 0.97]). Possession of a +331A allele was associated with an increased risk of implantation failure, which was nonsignificant overall but significant in women who weighed <135 pounds (adjusted relative risk, 3.85 [95% CI, 1.20, 12.30]). The +331G/A polymorphism tended to increase the risk for implantation failure in women with an H770H C/C genotype, but not in women with a C/T or TT genotype (P=.09). Among white women who were H770H C/C, there was a significant trend (P=.03) in the proportion of +331G/A carriers as the number of implantation failures increased, from 8.6% of women with 0 failed attempts to 40% among women with >or=5 failed attempts.
Conclusion: Although human progesterone receptor polymorphisms do not clearly affect the risk for implantation failure in most women who undergo in vitro fertilization, the likelihood that a woman carries the +331G/A human progesterone receptor polymorphism increases with the number of failed attempts at implantation.