Predictive Factors of Conception and the Cumulative Pregnancy Rate in Subfertile Couples Undergoing Timed Intercourse With Ultrasound
A retrospective cohort study was carried out to identify predictive factors for pregnancy along with the cumulative pregnancy rate (CPR) and live birth rate (CLBR) in subfertile couples undergoing timed intercourse (TI) using ultrasound.
Medical records of couples who underwent TI with ultrasound at the Severance Hospital Infertility Clinics between January 2017 to October 2019 were reviewed for study inclusion. Exclusion criteria ruled out women older than 43, male factor infertility (azoospermia, severe oligoasthenoteratozoospermia) and couples receiving subfertility treatment. Cycles in which intercourse was missed or ovulation did not occur was not included in final analysis. Regular menstrual cycles was defined as cycle length between 24 and 38 days.
Subfertility factors where assessed on day 2-5 of the menstrual cycle, with a full medical and reproductive history recording, serum hormone assays and baseline transvaginal ultrasound (TVUS), followed up with a hysterosalpingography at the end of menstruation. Male semen analysis was carried out twice, 4 weeks apart, after 2-4 days of abstinence.
Timed intercourse cycles were individualised according to standard protocols. Ovulation induction was initiated in couples with ovulatory subfertile factors while couples with non-ovulatory causes underwent either natural or ovulation induction cycles.
Ovulation induction was initiated using clomiphene citrate or letrozole, with gonadotrophins added in cases of poor follicular growth. Once one follicle reached 18µm in diameter, ovulation was triggered using human chorionic gonadotropin (hCG). Couples were advised to have intercourse 34 to 40 hours following hCG administration.
In this study, clinical pregnancy was defined as the presence of 1 or more gestational sac’s, confirmed by TVUS, 3 to 4 weeks after ovulation.
Initial analysis of pregnant and non-pregnant women baseline characteristics showed some significant differences, specifically a higher proportion of irregular cycles, shorter duration of subfertility (11.33 vs 17.6 months), lower serum FSH (7.14 vs 9.04 mIU/mL) and increased AMH (7.11 vs 4.99 ng/dL) among women who fell pregnant.
Of the 285 couples, 80 became pregnant over 854 cycles, resulting in a clinical pregnancy rate of 28.1% per couple and 9.4% per cycle. Final live birth rate was 23.2% per couple and 7.7% per cycle.
Advanced statistical analysis of the data showed that female age ≥ 35 years, duration of subfertility, serum basal FSH, unexplained infertility, uterine factors and endometriosis had a lower probability of conception. Female age ≥ 35 years had a 71% reduction in the probability of conception (odds ratio: 0.29), while a longer duration of subfertililty (≥24 months vs <12 months) also decreased the probability of conception by 81% (odds ratio: 0.19). Likewise endometriosis, compared to ovulatory factors, decreased the probability of conception by 71% (odds ratio 0.29) in the TI cycles.
Further analysis showed the cumulative pregnancy rates at cycle 1, 3, 6, 9 and 12 was 9.8%, 22,5%, 26.7%, 27.0% and 28.1% respectively. Similarly cumulative live birth rates at cycle 1, 3, 6 and 12 was 7.7%, 19.0%, 22.1% and 23.2%.
Cumulative pregnancy and live birth rates were highest in subfertile cases involving ovulatory factors reaching 39.81% (CPR) and 28.16% (CLBR), followed by unexplained factors (CPR 21.84%, CLBR 20.69%), uterine factors (CPR 23.73%, CLBR 23.73%) and endometriosis (CPR 16.67%, CLBR 13.89%).
Overall CPRs’ significantly increased until the fifth TI cycle, while CLBR’s significantly increased until the fourth TI cycle.
The authors concluded that couples who fail to achieve conception by the fourth or fifth cycle of TI with ultrasound may benefit moving onto the next treatment strategy.
SUMMARY: THE CHANCES OF GETTING PREGNANT WITH TIMED INTERCOURSE
The chances of getting pregnant with timed intercourse & ultrasound is highest in subfertile cases involving ovulatory factors (34.95% CPR), followed by uterine factors (20.34% CPR), unexplained infertility (19.54% CPR) and endometriosis (13.89% CPR). CPR, cumulative pregnancy rate by 5th TI cycle.
- No control group
- High drop out rate of patients
- Study size too small for further analyses of interest
Marshell M, et al. (2019). Stratification of fertility potential according to cervical mucus symptoms: achieving pregnancy in fertile and infertile couples. https://doi.org/10.1080/14647273.2019.1671613
Koo H S, et al. (2018). The likelihood of achieving pregnancy through timed coitus in young infertile women with decreased ovarian reserve. https://doi.org/10.5653/cerm.2018.45.1.31
Frank-Herrmann P, et al. (2017). Natural conception rates in subfertile couples following fertility awareness training. https://doi.org/10.1007/s00404-017-4294-z
Bouchard T P, et al. (2017). Achieving Pregnancy Using Primary Care Interventions to Identify the Fertile Window. https://doi.org/10.3389/fmed.2017.00250
Stanford J B, et al. (2008). Outcomes from treatment of infertility with natural procreative technology in an Irish general practice. https://doi.org/10.3122/jabfm.2008.05.070239
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