A miscarriage is classed as late when it occurs between the 12th and 24th week of gestation. If the miscarriage occurred at week 13 or later, it is sometimes called a second trimester miscarriage.
This type of miscarriage is less common than early miscarriages (around one in 100) as most pregnancies that are going to end do so before 12 weeks of gestation. So it can be very distressing for a woman to get to that stage in pregnancy, only to lose her baby.
Late miscarriages are more likely to be caused by a problem with the pregnancy, rather than a chromosomal abnormality in the baby. Possible causes could be:
Vaginal infection that then spreads to the amniotic fluid
Weakened Cervix – where the cervix cannot remain closed as the baby grows larger. This can be due to a previous cervical injury or a procedure such as a D+C or a termination, or it could be a condition that the woman was born with. This is also called cervical incompetence.
Placental Abruption – this is when the placenta that supplies oxygen and nutrients to the baby, comes away from the wall of the uterus. This causes the baby to lose its oxygen and circulation from the mother. This is also potentially life threatening to the mother as it can cause internal bleeding.
Blood clotting Disorders – if the mother produces too many antiphospholipid antibodies, then she will have a tendency to form blood clots. These may block off the baby’s oxygen or nutrient supply.
Amniocentesis – this is a test that is done to show if the baby has any genetic abnormalities. A needle is put through the abdomen to extract a sample of amniotic fluid for testing. This test carries a one in 200 to one in 400 risk of miscarriage.
Umbilical cord accident – this is where the cord accidently becomes wrapped around the baby’s neck and cuts off its oxygen supply.
Trauma – for instance, the mother is involved in a car accident.
Sometimes the baby may have a heart condition or other medical condition that results in a late miscarriage.
Symptoms of Late Miscarriage
With a late miscarriage, you will go into labor and deliver your baby.