Understanding ovulation
Q. My sorority sister gave me your contact information. I never had sex ed and biology is a blur from high school. I actually think they skipped reproduction! Here’s my concern. My boyfriend from college came to visit and we had unprotected sex. I know that’s not a wise choice, but it happened. It was one day after my period ended. Should I take a pregnancy test? It was four days ago. I’m not sure, I’m a little scared (only a little because we’re getting married after graduation in December). We both would be OK with the pregnancy but would like a little time as a married couple to get both our careers started and have time together. When should I take a test? I went online and got more confused. – 21-year-old
Mary Jo’s Response: I’m always sad when sexuality education isn’t available in schools; it’s even worse when a basic biology course ignores human reproduction. You have the right to understand your body.
Let’s talk about how ovulation works. It’s fascinating! Ovulation is part of the menstrual cycle – which has four phases: menstruation, the follicular phase, ovulation, and the luteal phase. Ovulation is the process when a mature egg (ovum) is released from the ovary. A follicle on the ovary bursts open, releasing the egg into the abdominal cavity. The fimbriae, which are finger-like projections at the end of the fallopian tubes closest to the ovaries, capture the egg during ovulation. The fimbriae pick up the egg and transport it into the tube. The egg will stay in the tube for 12 to 24 hours.
During that time, if unprotected sex happens, sperm may make their way to the tube and connect with the egg. If a sperm penetrates the egg, fertilization results. Tiny hairlike cilia lining the fallopian tube propel the fertilized egg (called a zygote) through the tube toward the uterus. The cells of the zygote divide repeatedly as the zygote moves down the fallopian tube to the uterus. The zygote enters the uterus in three to five days, becomes a blastocyst, and implants in the uterine wall six to 12 days afterward. About 10 to 12 days after fertilization, the blastocyst is called an embryo.
Hormones regulate the menstrual cycle – when the egg is released, the uterus begins preparing for a baby. The ovaries release hormones like estrogen and progesterone that cause the lining of the uterus to thicken in preparation for a fertilized egg. If the egg is not fertilized, the lining breaks down and bleeds, which is called a period. Menstrual blood is a combination of tissue and blood from the uterus.
A typical menstrual cycle lasts 28 days, but it can range from 21 to 38 days. Periods are considered regular if they occur every 24 to 38 days. Many people are confused as to when in the cycle ovulation occurs. To better teach this concept, I created a game where my students each wear a numbered 8-by-11 card around their necks. The numbers represent days in a menstrual cycle, and I move the students around the room, stopping to ask, “Which day is ovulation most likely now?” I’ve learned many of my students think ovulation occurs in the middle of the cycle, but this is only true if a woman has a very regular 28-day cycle. In reality, ovulation generally occurs about 12 to 14 days before the start of the next menstrual period, not 12 to 14 days after the last one begins.
The fact that your unprotected sex happened a day after your period ended tells me the chances of ovulation are very small, provided you have regular periods. Without ovulation, pregnancy cannot happen. I don’t think a pregnancy test is needed in your situation.
When taking a pregnancy test, it is most accurate to take it on the first day of a missed period. If you miss a period, you can take one. If you’re unsure of when your period is due, you can take the test 21 days after unprotected sex.
It sounds as if you and your boyfriend have solid plans for your future together. If you include preventing an unplanned pregnancy in those goals, your transition to married life will be smoother. Good luck.
Have a question? Send it to Dr. Mary Jo Podgurski’s email podmj@healthyteens.com.