Things have changed since most of us learned the facts about menstruation in school health class. Now, when nature isn’t enough, doctors can help women undergoing in vitro fertilization to achieve a “super cycle” to help them become mothers.
The menstrual cycle exists for humans to get pregnant and have babies. The regular rise and fall of hormones, the thickening of the uterine lining, and the release of an egg all lead to the possibility of a pregnancy with each (approximate) month. But when pregnancy doesn’t occur naturally and other treatments have been exhausted, in vitro fertilization (IVF) can sometimes help. An IVF cycle is different from a normal menstrual cycle. With IVF a woman takes drugs to suppress her own cycle, and replaces that basic biological process with one imposed by her doctor. The regular cycle is circumvented in the hopes that the new “super cycle” will achieve pregnancy.
All the things that happen in a normal fertility cycle also happen in an IVF cycle, but they occur differently, and at different times. Besides the phases of a regular menstrual cycle, an IVF cycle includes additional phases in which various hormones are taken to override the regular cycle and reset it so the chain of events can be controlled.
In an IVF cycle, scientists “mimic nature but improve on nature in both number of eggs produced, and timing that we are able to achieve,” says Daniel A. Potter, MD, medical director at the Huntington Reproductive Center in Southern California and co-author of the book, What To Do When You Can’t Get Pregnant (Marlowe and Company, 2005).
The Normal Cycle
A regular menstrual cycle occurs over approximately 28 days, and consists of three phases:
The Pre-Follicular Phase
This phase begins with the onset of menses and ends with the release of the egg (ovulation). During this time the follicles (egg-containing structures in the ovaries) begin to mature, but usually only one of these follicles will fully ripen and release an egg.
The egg is released. This usually occurs around day 14 of a 28-day cycle (or two weeks before menstruation in longer or shorter cycles).
The Luteal Phase
This phase begins with ovulation and ends with the onset of menstrual bleeding. During this time, the ruptured follicle (now called the corpus luteum) releases the hormone progesterone to maintain the thickened uterine lining and support early pregnancy. If pregnancy does not occur, the corpus luteum withers and dies…and the cycle begins again.