Читать книгу Dad's Guide to Pregnancy For Dummies - Sharon Perkins - Страница 43

Before she’s even born, a woman has all the eggs she’ll ever have. Unlike sperm, no new eggs are produced over time; the original eggs just mature, usually one at a time. Mature eggs are produced from immature ones (called oocytes), located in the ovaries, through a complex interaction of three hormones during the menstrual cycle. Those hormones — estradiol (a form of estrogen), follicle stimulating hormone (FSH), and luteinizing hormone (LH) — work like this:

1 Day 1 of the menstrual cycle begins when your partner’s period starts. FSH stimulates the ovaries, which produce estrogen.

2 Estradiol production starts to mature a number of egg-containing follicles, small, cyst like structures that contain the immature eggs.

3 One follicle, called a lead follicle, continues to develop while the rest atrophy.

4 Around day 14 of the menstrual cycle, LH kicks in to mature the egg and move it to the center of the follicle so it can release. Ovulation occurs 14 days before the last day of your partner’s cycle, so day 14 is based on an average 28-day cycle. If her cycles are longer or shorter than 14 days, she’ll ovulate earlier or later.

5 The egg releases from the follicle and begins to float down the fallopian tube. This is where you and your sperm come in.

If you’re interested in really getting into the nitty-gritty of how the menstrual cycle works, check out Getting Pregnant For Dummies by Lisa A. Rinehart et al (John Wiley & Sons).

Figure 2-1 shows the events of a menstrual cycle when pregnancy does not occur.

Illustration by Kathryn Born, MA

FIGURE 2-1: Every event in the menstrual cycle has a purpose.