No, menstruation does not occur when a woman is pregnant. The period only occurs when fertilization and implantation have not taken place, because if the embryo manages to implant in the endometrium, the pregnancy hormone is produced, which prevents the period from occurring.
If menstruation were to occur while the woman is pregnant, the baby would not be able to develop, since the placenta and the sac containing the baby would be detached from the uterus and expelled through the vagina.
Read the full article on: Is bleeding in pregnancy normal? What are the causes? ( 79).
Sara Salgado
B.Sc., M.Sc.
Embryologist
Degree in Biochemistry and Molecular Biology from the University of the Basque Country (UPV/EHU). Master's Degree in Human Assisted Reproduction from the Complutense University of Madrid (UCM). Certificate of University Expert in Genetic Diagnosis Techniques from the University of Valencia (UV).
