Does ART Timing Matter?
Getting pregnant is all about timing. Whether through natural conception or assisted reproductive technology (ART), getting that “big fat positive” depends on either having intercourse during the ovulation window or undergoing fertility treatments that are timed with a woman’s menstrual cycle. While natural conception only needs to accurately pinpoint ovulation, women undergoing ART will have menstrual cycles timed with treatments. Aspects from boosting ovulation production to thickening the endometrial lining, and even ovulation can all be controlled through treatments like in vitro fertilization (IVF) or intrauterine insemination (IUI). Depending on the method chosen, the entire experience can take anywhere from 4-8 weeks for a single cycle.
Preparing for fertility
The first step in fertility treatments is undergoing testing and screening to check for potential underlying problems such as an irregular period, poor sperm production, or even hormonal imbalances which might imply additional hormone therapy may be needed. With IVF, the experience can take 1-4 weeks and isn’t part of the active treatment cycle. With IUI timelines can vary depending on whether a patient is opting for natural or medicated IUI. Once the process begins for either method, medication is timed to key menstrual cycle phases to optimize egg production and prepare the uterus for insemination or embryo transfer.
Follicle stimulation
Follicle stimulation is a key component for IVF as well as medicated IUI and usually occurs between days 1-14. This process starts in the menstrual phase which is the first part of a woman’s natural cycle and is when the uterine lining is naturally shed. However, during this time, follicle stimulating hormone (FSH) begins stimulating the ovarian follicles to prepare for ovulation.
Triggering ovulation
In IVF and sometimes IUI a trigger shot is usually given between days 12-15. The medication is hormone stimulation through the use of human chorionic gonadotropin (hCG). Although naturally occurring, the hormone works to induce ovulation which would normally occur on day 14 of a woman’s natural cycle. With IVF, egg retrieval is typically scheduled within 36 hours of receiving the shot. In IUI, eggs are not removed from the body. Instead, insemination using either a partner or a donor sample is performed within 24-36 hours of the trigger shot.
Where IUI and IVF differ
After ovulation the two most common ART procedures look vastly different. After day 14, IUI becomes more like natural conception with patients undergoing the 2-week wait. The timeline is required for not just fertilization and embryo formation, but for implantation as well. The 2 weeks gives the body enough time for hCG to build up to detectable levels for a pregnancy test whether at-home or in-office. In IVF, fertilization occurs outside of the body with embryo transfer scheduled shortly after. Both steps are usually scheduled during the luteal phase of a woman’s cycle and take place between days 16-21.
Why timing matters
Even though ART treatments do allow for fertility specialists to somewhat manipulate or adjust hormone levels to optimize success rates, the processes still tend to follow the naturally occurring menstrual cycle timeline. As a result, synchronization is critical for achieving a positive outcome. With IUI, the first half of the menstrual cycle is more closely monitored while nature takes over in the back half since fertilization occurs in a woman’s body. By contrast, IVF is closely synchronized from start to finish with a 2-week wait that extends a woman’s cycle beyond the naturally occurring timeline.
