Women who have a bicornuate uterus often have challenges when they become pregnant. A bicornuate uterus is a birth defect that causes an indentation at the top of the organ, forming two separate chambers and giving it a distinct heart shape. It significantly increases the chances of miscarriage as the baby grows. There is a much higher likelihood that babies of these mothers will be born prematurely, and in many cases they end up in a breech position. Other possible complications include the potential for decreased fetal growth and increased likelihood that the placenta may become trapped in the uterus after the baby is born.
One of the main concerns with a pregnancy in a bicornuate uterus is that it will end in miscarriage. The top of the uterus is separated into two smaller sections, and if the fertilized egg implants in one of them, it will have much less room to grow and develop than normal. This greatly increases the chances that a spontaneous abortion will occur, placing the survival rate at around 60% for these pregnancies. The chances are better for success if the egg happens to implant in the larger section of the uterus.
For those pregnancies that are successful, there is still an increased risk of premature birth. Again, the decreased space within the uterus for the fetus to develop seems to play a role here, triggering labor early as there is less and less room for the fetus in the womb. There is a 15% to 25% greater chance of having a preterm delivery for women with a bicornuate uterus than for those without the condition.
The position of the baby can also be affected by this disorder. The lack of space once more becomes the a potential issue, making it uncomfortable for the baby to be head down or preventing it from turning, making a breech presentation more likely. This can in turn make labor more difficult or cause a caesarean delivery to be required.
There are other potential problems that can occur during pregnancy due to a bicornuate uterus as well. Though somewhat rare due to the greater chance of the pregnancy simply ending in miscarriage, a baby who does survive may not grow as much as it should due to limited space. There is also a greater chance there will be problems delivering the placenta after birth, making medical intervention necessary to remove it from the womb.