Fertility 101: getting pregnant
The menstrual cycle begins with the first day of a woman’s bleeding, and follicles begin to grow. By about the 6th to 10th day of the cycle, one follicle is in the lead and becomes dominant. (sometimes two will become dominant – if both eggs are ovulated and result in pregnancy, fraternal twins result) When the dominant follicle reaches maturity, about 14 days into the cycle, estrogen levels trigger the brain to release Leutenizing Hormone (LH) and the ovarian follicle ruptures and the egg is released. This process is called ovulation.
The egg is then captured by the delicate ends of the fallopian tube and waved toward the uterus. If sperm meet the egg in the fallopian tube and fertilize it, an embryo may result which is then carried through the tube toward the uterus where it may implant and result in pregnancy. If no sperm are present or fertilization does not occur, the unfertilized egg is expelled from the body when the next menstrual period occurs.
Natural conception rates per menstrual cycle are about 20% on average
Fertility is highest and conception most likely during the two days before the egg is released, and the day that the egg is released. This is because sperm may live for up to 5 days, and the egg is viable for less than 48 hours. Timing intercourse to the days before and during ovulation may increase your chance for pregnancy. Daily sex is not necessary, or recommended because sperm counts and motility on average are best with 18 to 24 hours between ejaculations. Natural conception rates per menstrual cycle are about 20% on average. That means that 2 in 10 couples trying each month will become pregnant, 8 will not. However, 85 to 90% of couples can expect to conceive within the first year of trying.
Infertility should be suspected if pregnancy does not occur within a year of unprotected intercourse, or in 6 months for women over 35.