Antimu¨ llerian Hormone as a Predictor of Natural Fecundability in Women Aged 30–42 Years Anne Z. Steiner, MD, MPH, Amy H. Herring, ScD, James S. Kesner, PhD, Juliana W. Meadows, PhD, Frank Z. Stanczyk, PhD, Steven Hoberman, MS, and Donna D. Baird, PhD, MPH OBJECTIVE: To generate estimates of the association 0.38; 95% confidence interval [CI] 0.08–0.91). The day- between markers of ovarian aging and natural fertility in specific fecundability for women with early-follicular a community sample at risk for ovarian aging. phase serum FSH values greater than 10 milli-interna- METHODS: Women aged 30–44 years with no history of tional units/mL compared with women with lower FSH infertility who had been trying to conceive for less than 3 levels was also reduced, although nonsignificantly (11% months provided early-follicular phase serum and urine of women affected; fecundability ratio 0.44; 95% CI Subsequently, these women kept a diary to 0.08–1.10). The association with urinary FSH was weaker .(100؍N) record menstrual bleeding and intercourse and con- (27% women affected; fecundability ratio 0.61; 95% CI ducted standardized pregnancy testing for up to 6 0.26–1.26), and the associations for the other markers months. Serum was analyzed for estradiol, follicle-stim- were weaker still. ulating hormone (FSH), antimu¨ llerian hormone, and in- CONCLUSION: Early-follicular phase antimu¨ llerian hor- hibin B. Urine was analyzed for FSH and estrone 3-gluc- mone appears to be associated with natural fertility in the uronide. Diary data on menstrual cycle day and patterns general population. of intercourse were used to calculate day-specific fe- (Obstet Gynecol 2011;117:798–804) cundability ratios. DOI: 10.1097/AOG.0b013e3182116bc8 RESULTS: Sixty-three percent of participants conceived LEVEL OF EVIDENCE: II within 6 months. After adjusting for age, 18 women (18%) with serum antimu¨ llerian hormone levels of 0.7 ng/mL or ocietal and behavioral shifts in recent years have less had significantly reduced fecundability given inter- course on a fertile day compared with women with Sresulted in a trend toward delayed childbearing. higher antimu¨ llerian hormone levels (fecundability ratio Women are choosing to delay attempts to conceive until they reach their 30s and 40s, ages associated with 1 From the Departments of Obstetrics and Gynecology and Biostatistics, University a lower probability of conceiving. The observed of North Carolina, Chapel Hill, North Carolina; the National Institute for decline in fecundability is the result of reproductive Occupational Safety and Health, Cincinnati, Ohio; the Department of Obstetrics aging, a natural progression through stages of pu- and Gynecology and Preventive Medicine, University of Southern California, Los Angeles, California; and the Epidemiology Branch, National Institute of berty, fertility, subfertility, the menopause transition, 2 Environmental Health Science/National Institutes of Health, Research Triangle and finally, menopause. The rate of movement Park, North Carolina. through these stages varies among individuals; women Supported by National Institutes of Health (NIH) R21 HD060229 and 5 K12 of the same chronologic age clearly differ in their HD050113 (University of North Carolina Women’s Reproductive Health reproductive potential, just as age at menopause varies Research Center). Also supported in part by the Intramural Research Program of the NIH, National Institute of Environmental Health Sciences (ie, support for between individuals. Despite variability in the age of coauthor D.B.). onset of subfertility, no validated biomarkers exist to Corresponding author: Anne Z. Steiner, MD, MPH, University of North monitor an individual woman’s fertility. Carolina, CB #7570, 4001 Old Clinic Building, Chapel Hill, NC 27599; Ovarian aging is associated with a decline in e-mail: [email protected]. oocyte number reflected by a decline in circulating Financial Disclosure The authors did not report any potential conflicts of interest. levels of antimu¨ llerian hormone and inhibin B and a rise in early-follicular phase follicle stimulating hor- © 2011 by The American College of Obstetricians and Gynecologists. Published 3–8 by Lippincott Williams & Wilkins. mone (FSH) and estradiol levels in blood. Although ISSN: 0029-7844/10 these markers are physiologically associated with 798 VOL. 117, NO. 4, APRIL 2011 OBSTETRICS & GYNECOLOGY changes in ovarian function, their ability to predict rolled and provided informed consent at their study fertility in the general population has never been visit, which was scheduled for the second, third, or rigorously examined. Previous research included only fourth menstrual cycle day (first day defined as the infertile patients, measured outcomes only after treat- first day of menses) after determination of eligibility. ment with assisted reproductive technology, or used Women who were determined to be eligible while menopause as the outcome. Despite limited support- using contraception were enrolled in the menstrual ing evidence, FSH levels are frequently measured at cycle immediately after cessation of birth control. doctors’ offices and in commercial home kits mar- At the study visit, women provided a urine and keted in the United States as a method of assessing blood sample. To prevent breakdown of FSH that one’s fertility. Commercial, dipstick kits measure FSH otherwise occurs in frozen samples, urine (5 mL) was in urine. A positive test is noted when urinary values transferred to a polypropylene vial containing glyc- exceed the cutoff value equivalent to a serum value of erol (7% final glycerol dilution).11 The serum and 10 milli-international units/mL. These unproven tests urine samples were stored frozen at Ϫ80°C until have the potential to lead to unnecessary treatment or analysis. At the study visit, participants were also false reassurance, induce anxiety, and result in inap- provided and instructed on the use of the study diary, propriate costs and inconvenience to consumers if the which was designed to collect daily information on 9 tests are not valid. vaginal bleeding, intercourse, pregnancy test results, Fertility of individuals can be compared a num- and medication use. Participants were asked to com- ber of ways. Relative fecundability, the difference in plete the diary daily until pregnancy was detected or fecundability (probability of conceiving in a men- three menstrual cycles had passed. In addition, strual cycle) of one group compared with another, is women were provided with free home pregnancy estimated by analyzing data on time to pregnancy, the tests (sensitivityϭ20 milli-international units human number of menstrual cycles required to conceive. chorionic gonadotropin/mL) and instructed to use Because retrospective assessments of time to preg- them at the time of missed menses. nancy are subject to strong bias effects,10 prospective Women were instructed to inform study staff of a studies are preferable. If information on menstrual positive pregnancy test. Women were provided a free bleeding and intercourse is also collected, time to pregnancy ultrasonography to encourage notification pregnancy studies can be used to compare day- of pregnancy results. Women who did not report a specific probabilities of pregnancy for affected and unaffected individuals or the relative probability of positive pregnancy test were contacted at 3 and 6 pregnancy given an act of intercourse on a fertile day. months after the study visit. Women were followed Because specific endocrinologic changes appear until a positive pregnancy test or until 6 months of to reflect ovarian aging, which is the presumed major attempt after the study visit. cause of decline in fecundability, we sought to esti- Urine was shipped frozen to the National Institute mate the association between endocrine indices of for Occupational Safety and Health Reproductive ovarian aging (early-follicular phase FSH, estradiol, Endocrinology Laboratory, where the samples were antimu¨ llerian hormone, and inhibin B in serum as assayed for FSH, estrone 3-glucuronide, and creati- well as FSH and the estrogen metabolite, estrone nine. Urinary FSH concentrations were assayed in 3-glucuronide in urine) and fecundability in a com- duplicate using a noncompetitive, two-site time-re- munity sample at risk for ovarian aging. solved immunofluorometric assay.12 Urinary estrone 3-glucuronide concentrations were measured in trip- MATERIALS AND METHODS licate using competitive double-antibody time-re- Time to Conceive, a time to pregnancy study, was solved fluoroimmunoassay developed and character- approved by the institutional review board of the ized in the National Institute for Occupational Safety University of North Carolina. English-speaking and Health laboratory.13 Urinary creatinine concen- women between 30 and 44 years of age, who were trations were measured using a Vitros 250 Chemistry attempting to conceive for 3 months or less or were Analyzer that uses a slide composed of a dry, multi- about to start trying to conceive, were eligible for layered analytical element coated on a polyester participation in the study. Women with a history of support. Urinary endocrine values (FSH and estrone infertility, polycystic ovarian disease, pelvic inflam- 3-glucuronide) were divided by the respective sam- matory disease, endometriosis, pelvic radiation, or ple’s creatinine concentration to adjust for urine flow with a partner with a history of infertility were ex- rate. All samples were measured in one assay per cluded