How likely is it to get pregnant on or around your period? If so, how does it come about?
Usually, a period is considered to be a safe time to have sex, for someone who doesn’t want to get pregnant. The chances of fertility are considered low during this period. But sometimes, pregnancy can occur while having a period.
Menstruation, ovulation and conception, all occur due to changing balance of the hormones estrogen and progesterone within the body.
Conception occurs when a sperm enters the body after intercourse and meets an egg, resulting in fertilisation. Ovulation usually occurs during 14th to 21st day from the first day of menstrual period, i.e. beginning of bleeding. But ovulation may occur as early as 3rd to 5th day of finishing a menstrual cycle. The egg survives only 12 to 24 hours after release, a sperm can survive for three to five days within body and can survive in menstrual blood. Therefore, if a woman does intercourse on last day of menstrual period or even before, she can conceive, just on availability of an egg meeting a sperm resulting in fertilisation. This applies to women having regular menstrual cycles.
But in case of women having irregular cycles, it becomes difficult to ascertain time of ovulation. Thick cervical mucus, increased basal body temperature, are self-help measures to determine it, but they are not always 100% accurate.
Hence, a woman may conceive any time, during or immediately after a menstrual cycle. Stress, smoking, irregular sleep, wake cycles, obesity, thyroid disorders, ovarian disorders, and et cetera, are some of the factors that can affect menstrual cycles and time of ovulation.
The change in hormone balance may be slow or inadequate in some women. Thus, one may conceive and have some bleeding, which may be mistaken for a menstrual cycle.
Though considered a safe period, sometimes a woman can conceive during menses. Chances of conception depend on length, duration and regularity of menstrual cycle. When did a woman have sex, did she ovulate on that day or immediately before or after, are other factors which determine, whether conception occurs during menstruation or not. Someone not wanting to conceive should always use some protection, while having sexual intercourse, irrespective of presence of menstrual cycles.
Dr. Rachna Pande is a specialist in internal medicine.