The fertilization process is the same whether a singleton or a twin pregnancy occurs. The difference is that after fertilization, the embryo splits in two. Therefore, the babies will have the same genetic material, so they will be of the same sex.
On the other hand, twins can have different sexes since they have half of the genetic material different. In this case, what happens is that two eggs are fertilized, each by one sperm.
Read the full article on: What Are the Steps of Fertilization in Humans? ( 84).
By Laura de la Fuente Bitane M.D. (gynecologist), Marta Barranquero Gómez B.Sc., M.Sc. (embryologist), Zaira Salvador B.Sc., M.Sc. (embryologist) and Romina Packan (invitra staff).
Last Update: 04/10/2024