Ovarian reserve assessment in users of oral contraception seeking fertility advice on their reproductive time span
To what extend does oral contraception (OC) impair ovarian reserve parameters in women who seek fertility assessment and counselling to get advice on their remaining reproductive time span?
Ovarian reserve parameters were found to be significantly reduced among users of OC compared to non-users. Anti Müllerian Hormone (AMH) and Antral Follicle Count (AFC) were decreased by 28% and 31%, respectively, whereas the reduction in ovarian volume ranged from 29-53%, being most pronounced in the group 35-39.9 years.
What is known already
AMH and AFC have proven to be reliable predictors of ovarian ageing and onset of menopause. In women, AMH declines with age and data suggests a clear relationship
with remaining reproductive life span and age at menopause. OC may alter parameters related to ovarian reserve assessment, but the reduction in the various parameters is more uncertain.
Study design, size, duration
A prospective, population-based, cross sectional cohort study of the first 500 women aged 20-45 years seeking fertility counselling at the Fertility Assessment and Counselling Clinic (FACC) at Copenhagen University Hospital from 2011 to 2013. The study compared AMH, AFC and ovarian volume in users and non-users of OC.
Participants/materials, setting, methods
The FACC was initiated in order to provide individual fertility assessment and counselling. The first 500 consecutive women were included in the present study. All women were examined by a fertility specialist, who performed a transvaginal ultrasound (AFC, ovarian volume, pathology) uptake of a full reproductive history and AMH measurement.
Main results and the role of chance
Among the 500 women, the proportion of OC-users was 133 (26.6 %). The ovarian volume was markedly reduced in all OC-users ranging from 29% to 53% with the most
pronounced reduction in the age group 35-39.9 years (p<0.0005) . In linear regression analyses with adjustment for age, AMH was 28% (95% CI 10-50%) lower and AFC was 31% (95% CI 17-46%) lower in OC-users compared to non OC-users. Furthermore, we found a significant decrease in antral follicles sized 5-7 mm (p< 0.001) and antral follicles sized 8-10 mm (p<0.0001) among OC-users, but no decrease in antral follicles sized 2-4 mm (p<0.247). The two groups (OC-users vs. non-OC-users) were comparable regarding age, BMI, smoking and maternal age at menopause.
Limitations, reason for caution
The study population consisted of women attending the FACC with a concern about their ovarian reserve and reproductive time span, which could imply a potential
selection bias. Both AMH and AFC can be assessed independently of the cycle, but documentation of the accuracy in predicting residual reproductive time span is still needed.
Wider implications of the findings
Oral contraception has a major impact on the ovarian volume, and a moderate impact on AFC and AMH with a shift towards the small size in antral follicle subclasses. The most evident reduction occurs in the AMH producing follicles (5-7 mm and 8-10 mm follicles), which have the highest number of AMH secreting granulosa cells. Knowledge on these changes in ovarian morphology is important when using ovarian reserve parameters for counselling on reproductive time span.