Miscarriages in the second trimester are much less common than first trimester miscarriage. Chromosome problems could still be the cause, but this is less likely in late pregnancy loss. There are some unique causes of pregnancy loss in the second trimester.
If you know or suspect you have a weak cervix, uterine defect or clotting disorders, or if you have previously had a miscarriage, consult with your doctor before becoming pregnant to discuss what can be done to reduce your chances of miscarriage in the early and later stages of pregnancy.
Some women have a weak cervix, they can be born with it or it can become weak after surgery on the cervix. Surgery on the cervix could have been due to abnormal pap smears requiring biopsies, multiple pregnancy terminations or D & C’s.
When the cervix is weak it can begin to dilate without any symptoms. As the pregnancy progresses, more pressure is put on the cervix and over a period of time it dilates. If this goes on not noticed and untreated the result will be an unexpected and rapid delivery of the fetus.
Uterine defects can cause a second trimester miscarriage. There are a few conditions such as bicorneate (heart-shaped) uterus and uterine didelphys (the uterus is divided in two) which can cause the uterus to not be able to expand properly in order to retain the pregnancy as it progresses and grows.
When uterine defects are identified, surgery can help correct these abnormalities to decrease the chance of late miscarriage in future pregnancies.
Medical illness of the mother can contribute to a miscarriage. Some of these include kidney, cardiac, blood pressure and clotting disorders.
Severe high blood pressure and chronic high blood pressure can increase the risk for preeclampsia. Preeclampsia is not just high blood pressure, it also presents with protein in the urine. The risks to the mother’s health must be weighed as this can be a life threatening condition and the only cure for preeclampsia is to deliver the baby.
Women who have clotting disorders like antiphospholipd syndrome, lupus anticoagulant or anticardiolipin antibody syndrome are at risk for recurrent pregnancy loss in the second trimester. The placentas of women with these conditions have been studied and multiple small clots were present. The use of anticoagulant therapy (blood thinners) is being studied as treatment.