Tare wrote:
Of course, not everyone's LP is 14 days. Oh, the complexity of it all. This is where ovulation predictors come in handy, as Ambrya discussed. Once you see she's ovulating, you know what to do.
Exactly. This is where both charting and OPKs helped Mr. Ambrya and I out, because even though I generally have a 26-27 day cycle, I don't ovulate until around day 18, which makes my luteal phase (the time between ovulation and menstruation) quite short.
A short LP can be problematic because if a fertilized ovum takes 7-10 days to implant, it BARELY has enough time to do so if your LP is less than 10 days. It's entirely possible that even with perfectly timed intercourse, a woman with a short LP won't get pregnant because she begins menstruating before the blastocyst (the ball of cells the fertilized ovum develops into as it makes its way down the uterine tube) has a chance to implant.
Shortened LP can also indicate that the corpus luteum isn't producing enough progesterone, because it's when progesterone drops below a certain threshold that menstruation begins, and it's faster to drop below that threshold if there's not all that much of it to begin with. Low progesterone production can be a problem if implantation does manage to occur, and can lead to early miscarriage.
Basically, progesterone is the primary hormone involved in supporting and maintaining pregnancy. During the luteal phase, the corpus luteum produces it. During this time, it is responsible for the buildup of the nutrient-rich endometrial lining in which the blastocyst might implant. If there is no implantation, the corpus luteum degenerates and stops production, and menstruation begins.
If implantation DOES occur, the implanted blastocyst (now called an embryo) begins pumping out hCG (human chorionic gonadotropin--the hormone pregnancy tests checks for) and hCG tells the corpus luteum NOT to degenerate, but instead continue producing progesterone. Progesterone at this stage serves the function of pumping nutrients to blood vessels in the endometrium, and forming the maternal side of the placenta (the placenta doesn't form right away, it usually isn't fully formed until close to the end of the first trimester--about 10 weeks or so.) Once the placenta is formed, it takes over progesterone production and the corpus luteum degenerates.
If the corpus luteum isn't producing enough progesterone, the embryo can basically starve for nutrients before the placenta has a chance to form.
So, knowing how late in the cycle Mrs. Aadynn ovulates can also help you know when or if it's time to talk to her OB about getting some help.
Sorry if I'm giving more information than you wanted--you've got me started on my favorite subject, both personally and professionally. Edited, Nov 18th 2006 at 10:58am PST by Ambrya