Yes, it is possible to get pregnant while already pregnant, though it is an extremely rare phenomenon known as superfetation.
What is Superfetation?
Superfetation occurs when a second, new pregnancy begins during an existing pregnancy. This means that an individual conceives again while already carrying an embryo or fetus, leading to two fetuses of different gestational ages developing in the uterus simultaneously. Unlike typical twin pregnancies where two eggs are fertilized at or around the same time, superfetation involves two separate fertilization events that happen weeks or even months apart.
Why is Superfetation So Rare?
The human body is remarkably efficient at preventing subsequent pregnancies once conception has occurred. Several natural mechanisms typically prevent superfetation from happening:
- Hormonal Suppression of Ovulation: After conception, the body undergoes significant hormonal changes. Hormones like progesterone rise, which usually prevents the ovaries from releasing any more eggs (ovulation). Without a new egg, a subsequent pregnancy cannot occur.
- Cervical Mucus Plug: The cervix, the opening to the uterus, forms a thick mucus plug early in pregnancy. This plug acts as a barrier, preventing sperm from entering the uterus and reaching any newly released eggs.
- Uterine Environment Changes: The uterus itself transforms to support the developing pregnancy, becoming a less hospitable environment for a new embryo to implant and grow. The lining of the uterus is already occupied and undergoing changes to sustain the first pregnancy, making it difficult for a second fertilized egg to successfully implant.
Given these robust preventative measures, cases of superfetation are so uncommon that they often attract significant media attention when they do occur. It signifies that, in rare instances, one or more of these protective mechanisms have failed, allowing for a second, separate conception.
