Antral follicle count as a marker of ovarian biological age to reflect the background risk of fetal aneuploidy

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Abstract

STUDY QUESTION

Can antral follicle count (AFC) measured during pregnancy be used as a marker of ovarian age to assess the background risk of fetal aneuploidy?

SUMMARY ANSWER

AFC was lower than expected according to maternal chronological age in trisomic pregnancies; therefore ovarian age could potentially reflect a more precise background risk of fetal aneuploidy screening.

WHAT IS KNOWN ALREADY

The decline in a woman's reproductive function is determined by a decline in the ovarian follicle pool and the quality of oocytes. The quantitative status of ovarian reserve can be indirectly assessed by AFC, but the role of AFC as an aneuploidy risk marker in pregnant women has not been assessed yet.

STUDY DESIGN, SIZE, DURATION

Our study comprised a prospective cohort including 1239 singleton pregnancies scanned before 14 weeks in our center during a 14-month period.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Reference ranges for AFC were constructed using 812 spontaneously conceived, chromosomally normal singleton ongoing pregnancies using the Lambda-Mu-Sigma method. The study population (n = 934) included 19 pregnancies with viable autosomal trisomies (trisomies 21, 18 and 13), 17 non-viable autosomal trisomies (other than 21, 18 or 13), 7 monosomies X, 1 sex trisomy and 3 triploidies (total n = 47 with chromosomal abnormalities). AFC in chromosomally abnormal pregnancies was plotted against the reference ranges. AFC multiple of the median was calculated according to the median AFC obtained by each year of age.

MAIN RESULTS AND THE ROLE OF CHANCE

Sixty-eight percent of women carrying a pregnancy with viable trisomies and 65% with non-viable trisomies presented an AFC below the 50th percentile. The median ovarian age in viable trisomies and non-viable trisomies was estimated to be 3 and 6 years above than median maternal age, respectively. However, the median ovarian age in monosomies X and triploidies was not higher than median maternal age.

LIMITATIONS, REASONS FOR CAUTION

We did not assess the intra- and inter-observer reliability, or use specific three-dimensional analysis which may have advantages over our two-dimensional study. In clinical practice, a drawback for assessing AFC during pregnancy is that transvaginal ultrasound is needed at the 11- to 13-week scan, when the transabdominal approach is used most commonly. Furthermore identifying ovaries by ultrasound during pregnancy could be challenging.

WIDER IMPLICATIONS OF THE FINDINGS

Considering that AFC reflects ovarian aging, this ‘ovarian biological age’ could potentially reflect a more precise background risk of fetal aneuploidy.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by PI 11/00685. Instituto de Salud Carlos III. Fondo de Investigación Sanitaria. No competing interests declared.

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