Does Menstruation Mean You Can't Get Pregnant? Pregnancy Myths

The onset of menstruation typically indicates that pregnancy has not occurred?

Hello, doctor: I am a 21-year-old mother.
Due to my previous irresponsible behavior, I am now feeling anxious every day.
My baby is almost 4 months old.
I accidentally had sexual intercourse with my ex-boyfriend on May 15 of last year, but I got my period on June 27.
However, I forgot whether the flow was heavy or light.
June 27 was the last period before my pregnancy! The doctor calculated my due date to be March 29 of this year, but my baby was born on March 31.
My blood type is A, and my current husband's blood type is B, yet my baby is O type.
Although it is possible for A and B types to have an O type child, I heard from friends that my June 27 period might have been a false period.
Additionally, since I had an accidental encounter with my ex-boyfriend, even though he said he used a condom, I am still worried because it was quite close in time.
After that, I had several instances of intercourse with my current husband, but I am still concerned that the baby may not be my current husband's.
I feel anxious all the time.

Xiao Mi, 20~29 year old female. Ask Date: 2008/07/18

Dr. Li Guanghan reply Obstetrics and Gynecology

Hello!!! You may consider undergoing a paternity test.
Wishing you peace and safety.

Reply Date: 2008/07/18

More Info

Menstruation does not necessarily mean that you cannot get pregnant, and understanding the nuances of this topic can help alleviate some of the anxiety surrounding it. Let's break down the key points regarding menstruation, ovulation, and pregnancy.

Firstly, menstruation is a part of the menstrual cycle, which typically lasts about 28 days but can vary from person to person. The cycle consists of several phases: the follicular phase, ovulation, the luteal phase, and menstruation. Ovulation usually occurs around the midpoint of the cycle, when an egg is released from the ovary. This is the time when a woman is most fertile and has the highest chance of becoming pregnant if she has unprotected intercourse.

If you have your period, it generally indicates that you are not pregnant at that time. However, it is important to note that some women may experience bleeding during early pregnancy, which can sometimes be mistaken for a menstrual period. This is known as implantation bleeding and occurs when the fertilized egg attaches to the uterine lining. Therefore, if you had unprotected intercourse close to your ovulation period, there is still a possibility of pregnancy even if you experience bleeding afterward.

In your case, you mentioned that your last menstrual period before your baby was born was on June 27, and your estimated due date was March 29. Since your baby was born on March 31, this timeline aligns with a typical gestation period of about 40 weeks. The fact that you had a menstrual period does not negate the possibility of becoming pregnant from the encounter with your ex-boyfriend, but the timing of your cycle suggests that you likely conceived after that date, especially if you were actively trying to conceive with your current partner.

Regarding the blood type of your baby, it is indeed possible for an A-type mother and a B-type father to have an O-type child. Blood type inheritance follows specific genetic patterns, and the ABO blood group system is determined by the alleles inherited from both parents. Therefore, the presence of an O-type child in your case is genetically plausible.

Your concerns about the paternity of your child are understandable, especially given the circumstances surrounding your previous relationship. However, if you have been in a committed relationship with your current husband and have had unprotected intercourse, the likelihood of your baby being his is high, particularly if you were not pregnant at the time of your last menstrual period.

If you are still feeling anxious about this situation, it may be beneficial to discuss your concerns with a healthcare professional. They can provide reassurance and possibly suggest a paternity test if you feel it is necessary for your peace of mind. Remember that open communication with your partner about your feelings and concerns can also help alleviate some of the stress you are experiencing.

In conclusion, menstruation typically indicates that you are not pregnant, but it is not an absolute guarantee. Understanding your menstrual cycle, ovulation, and the possibility of early pregnancy symptoms can help clarify your situation. If you have further concerns, consulting with a healthcare provider can provide additional support and guidance.

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