Quantifying effect of combined oral contraceptive pill on functional ovarian reserve as measured by serum anti-Müllerian hormone and small antral follicle count using three-dimensional ultrasound.

OBJECTIVES: Oral contraceptive pills suppress the hypothalomo-pituitary axis, which can affect the ultrasound and endocrine markers used to examine ovarian reserve. The objective of this study was to quantify the ultrasound and endocrine markers of functional ovarian reserve in women using a combined oral contraceptive pill (COCP) for more than a year.
METHODS: This was a prospective case-control study involving healthy volunteers: 34 women using for more than a year a COCP with hormone-free interval (HFI) were compared to 36 normo-ovulatory, age-matched controls who had not used hormonal contraception within the last year. Volunteers using a COCP underwent a 3D ultrasound examination and had a blood sample taken within the first 4 days of active pill ingestion and those in the control group had the scan and blood test in the early follicular phase (days 2-5) of menstrual cycle. The main outcome measure was the difference in antral follicle counts stratified according to size and anti-Müllerian hormone (AMH), follicle-stimulating hormone (FSH), luteinizing hormone (LH) and estradiol (E2) levels.
RESULTS: There were no significant differences in the number of small antral follicles measuring 2-6 mm. The COCP group had significantly fewer antral follicles measuring ≥ 6 mm (P < 0.001) and had significantly smaller ovaries (P < 0.001), which also had lower vascular indices than the control group (P < 0.05). While serum FSH, LH and E2 levels were significantly lower in the COCP group (P < 0.05), there was no significant difference in serum AMH levels between the two groups.
CONCLUSIONS: Prolonged use of COCP suppressed pituitary gonadotropins and antral follicle development beyond 6 mm, but had no effect on levels of serum AMH and number of small antral follicles.