The study finds that pregnancy occurs faster with IVF but given sufficient time, intercourse alone will equal IVF. It takes about 3 years to match IVF rates.
IVF works faster even though the assumptions regarding the IVF success rates used in the study are are incredibly low by NCRS standards. Our success rates far exceed those by the Dutch that the authors use and intercourse would not even be close using the numbers of a highly successful IVF center – or even the US IVF average. The study maxes the IVF success at 50% after 3 attempts and 2 more years of intercourse.
The data for the intercourse is reasonable but then they used a extremely conservative IVF success rate so that the intercourse model caught up much quicker than it should. Further, my patients are generally not going to wait 3 years to see if they get lucky without intervention.
Some of my patients are willing to take a very conservative hands-off approach and this data gives us some idea of the cumulative success rate in those scenarios. The conservative approach is great for those willing to be patient (and hopefully young so that if they fail to conceive then there is time for intervention).
Study conclusions: In couples without clear indications for IVF, the main benefit of early IVF may be to shorten time to pregnancy, a benefit that must be weighed against costs and potential adverse outcomes. Couples should be encouraged to maintain regular intercourse to maximize chances of pregnancy, even after unsuccessful treatment attempts.
Study groups and assumptions
- Relatively frequent intercourse: Couples continue attempting pregnancy with the same intensity as during the initial 2 years but do not seek additional treatment beyond appropriate timing of intercourse.
- Less frequent intercourse: Couples continue attempting pregnancy but are less diligent in frequency or timing of intercourse; we assumed a reduction in frequency of intercourse resulting in a 40% reduction in probability of pregnancy per cycle. This estimate is what would result from a reduction in the average frequency of intercourse from two times per week to one time per week.
- Conservative treatment: Couples apply a conservative treatment which improves their natural chances of getting pregnant; we assume an improvement by a factor of 1.5 as a multiplicative effect on the probability of pregnancy per cycle.
- IVF treatment for up to three cycles, each lasting on average the equivalent time of three natural or conservative cycles, followed by less frequent intercourse. They used Dutch data suggesting that after 1 year or an average of 1.8 cycles then 43% would have a baby.
- Conservative treatment for 20 cycles, followed by IVF treatment for up to three cycles, each lasting on average the equivalent time of three conservative cycles.