If you thought the one benefit of having your period was that you can’t get pregnant, you’re not going to like this: You can absolutely still get pregnant on your period.
First, a quick biology lesson. Your menstrual cycle is split into three parts: the follicular phase, ovulation, and the luteal phase. The follicular phase starts on day one of your period, when you shed, then rebuild, your uterine lining. “This phase of the cycle can be short for some women and longer for others,” says Dr. Karen Brodman, an ob-gyn in New York. “But it typically lasts 14 to 21 days.” Then, you ovulate (when one ovary releases an egg into your uterus). At this time, you might notice some symptoms of ovulation, such as sore breasts, increased hunger, and changes in libido.
The next phase is the luteal phase, which starts right after ovulation. Progesterone increases, priming the uterine lining for pregnancy. Unlike the follicular phase, the luteal phase of the cycle is not variable and always lasts 14 days. When you don’t get pregnant, your estrogen and progesterone levels drop, your uterus starts shedding its lining, and your period starts, Dr. Brodman says. That puts you right back at day one of your cycle.
Now, let’s address why you can still get pregnant on your period.