Ovulation is the event in a woman’s menstrual cycle when an ovary releases an egg. The egg then travels through one of the fallopian tubes toward the woman’s uterus for implantation. The egg will only implant in the uterus if it is fertilized by sperm.

The rhythm method of birth control refers to having sex during a “safe period” in a woman’s cycle. It can work, but it tends to be tedious and must be followed with 100 percent precision to be reliable.

To successfully practice the rhythm method, a woman must keep track of three things: cervical secretions, basal body temperature, and the fertile days of her cycle.

For the method to work, a woman must abstain from sex for a few days before and after her fertile time period. But one small miscalculation can lead to pregnancy with this technique.

My experience with patients using the rhythm method has not been great — which is to say that there have been unplanned pregnancies.

I do think a committed couple can successfully follow the rhythm method, but it takes a special person or a special relationship to practice this technique without mistakes.