Can You Get Pregnant Even If You're Not Ovulating?

The average fertility cycle lasts 28 days, with the first day of menstruation signifying day one. Every cycle, the uterine lining builds up in the few days before ovulation. If implantation of a fertilized egg doesn't occur, the lining will shed in the form of another menstrual period in about two weeks.

Time Frame

During the average 28-day cycle, three phases dictate when and if you can get pregnant. Though ovulation is only one day, a woman may be fertile for up to 7 days. The average woman will ovulate on day 12 to 14; however, pregnancy can still occur if she has sex within a few days prior to ovulation, as her uterus has fertile mucus to trap and hold sperm. Once the egg is released, live sperm can still fertilize the egg. Understanding the phases of fertility is the first step toward understanding whether or not you may be fertile.

Phase One

Phase one is a time of pre-ovulation infertility. During this time, a woman menstruates; however, toward the end of this phase, intercourse may result in pregnancy. Once menstruation starts, the pituitary gland releases the follicle-stimulating hormone--FSH--which will help to develop an ovarian follicle and the ovum it contains. After this, the ovarian follicle secretes estrogen. Estrogen will then prepare the uterus for ovulation. Though menstruation is typically an infertile time, the further a woman gets from the day of menstruation, the closer she is to ovulation. The end of this phase is marked by signs of impending ovulation, and sperm with a longer life may have the ability to fertilize an egg if intercourse takes place. According to John and Sheila Kippley, authors of "The Art of Natural Family Planning," most unexpected pregnancies occur at the end of phase one, though a woman has not yet ovulated.

Phase Two

The most fertile time of a woman's cycle, phase two may start as early as day 8 or 9. The starting of phase two is signified by an increase in cervical mucus, both internal and external. Also, an upward shift in basal body temperature of 0.4 degrees indicates that ovulation has occurred. During this time, pregnancy is very likely, though the egg is only released for one day of this phase. Sperm live for 3 to 7 days, so an average woman will have approximately as many as 7 days where sexual intercourse can result in pregnancy. During this time, a woman's cervical mucus is long and stretchy to help promote sperm mobility.

Phase Three

Also called the luteal phase, phase three is the infertile time after ovulation. A woman can know that ovulation is over when her cervical mucus has been dry for about 2 days, and she's had at least 3 days of high basal body temperatures. Once the egg dies, it becomes a corpus luteum and secretes progesterone. Progesterone maintains the cervical lining, causes the basal body to remain elevated and suppresses a subsequent ovulation in that cycle. This phase will last for about 10 to 14 days, and women are infertile during this phase. In an average cycle, the luteal phase will start between days 14 and 18.