When a fertilized egg implants in the uterine lining, pregnancy occurs. When you are pregnant it is not possible to have another pregnancy because once an egg is fertilized and implanted in the uterus, a high level of hormones – estrogen and progesterone secreted by the corpus luteum and placenta inhibits the secretion of gonadotropins(LH and FSH) and prevent ovulation and menstruation process. Thus both the ovarian and menstrual cycles remain suspended during pregnancy.
There is the formation of a thick cervical mucus plug during pregnancy which seals the cervical canal and prevents the entry of sperm during intercourse. It helps to prevent another pregnancy while you’re pregnant.
In extremely rare conditions, when you are already pregnant, you can get pregnant again through the phenomenon called superfetation and superfecundation.
This process involves the fertilization of two ova released in different menstrual cycles. Sometimes in very rare conditions due to unknown reasons, your body may have an ovulation cycle even after the fertilized egg has been implanted once. If you have sexual intercourse with your partner during ovulation time, sperm fertilizes another ova and you can get pregnant again with two babies. Both the babies will be having different stages of development and gestation.
Implantation and development of one baby over another baby are theoretically possible until the uterine space is obliterated by 12 weeks of pregnancy.
A few confirmed cases of superfetation in pregnant women have been identified by medical experts as it is a very rare occurrence.
This process involves the fertilization of two different ova released in the same ovarian cycle, by a separate act of sexual intercourse within a short period of time.
Both the phenomena, superfetation and superfecundation are very rare occurrences and only a few cases are yet reported.
In the above post, we discussed the phenomena of superfecundation and superfetation behind re-pregnancy when you are already pregnant.