What Happens During a Miscarriage?

Experience varies by the cause or timing of pregnancy loss

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Miscarriage is the natural loss of pregnancy before 20 weeks. It occurs in between 10 percent and 20 percent of all known pregnancies and most often before the 13th week.

The experience of miscarriage can vary by the cause and timing of the loss. Those that occur in early pregnancy can be quite different from those in the second or third trimester. It some cases, it can happen almost invisibly as with so-called missed miscarriages which have no outward symptoms.

The First Trimester Miscarriage

In most first trimester miscarriages, the embryo or fetus stops developing early on. The woman's body will recognize that the pregnancy is no longer viable and begins to shed the uterine lining. This is the process that causes the tell-tale signs of miscarriage, namely cramping and vaginal bleeding.

Not all women will have these symptoms or experience them as profoundly. In some cases, the bleeding may be mild. Others may experience more subtle signs, such as the sudden loss of morning sickness or breast tenderness. For others still, weeks may pass before any signs or symptoms appear.

If pregnancy loss occurs during the first trimester, an ultrasound and/or blood tests may be used to confirm the diagnosis. Depending on the timing or cause, the woman may choose to complete the miscarriage naturally or seek assistance in the form of medications or a surgical procedure called dilation and curettage (D&E).

The Threatened Miscarriage

In most miscarriages, the baby's heart will have stopped beating before the outward symptoms of miscarriage appear. However, in some cases, vaginal bleeding will occur when the heartbeat is still detectable and the cervix is still closed. This is called a threatened miscarriage.

In most cases, the bleeding will stop and the pregnancy will remain viable. In others, the threatened miscarriage will end in loss. There is really no way to predict the outcome. While some doctors will recommend rest and the avoidance of sex, exercise, tampons, and heavy lifting, there is little evidence that this helps.

As with pregnancy itself, there’s often little rhyme or reason as to why some threatened miscarriages end in loss and others remain viable to term.

The Second Trimester Miscarriage

Early second trimester miscarriages are treated in much the same way as the first. However, as the fetus will be further along in its development, the loss will typically be confirmed by the lack of a fetal heartbeat.

The causes of miscarriage in the second term can include cervical insufficiency (the premature dilation of the cervix) or preterm labor (also known as premature birth).

  • With cervical insufficiency (also known as an incompetent cervix), the baby is born too early to survive. Doctors can sometimes delay or prevent delivery with a cervical cerclage (a stitch used to hold the cervix closed), but only if the condition is detected early.
  • With preterm labor, doctors can sometimes halt the process with anti-contraction medications and bed rest if, again, the signs are spotted early.

    Pregnancy loss in the second trimester can also be the result of maternal infection (bacterial vaginosis, amniotic infection), congenital conditions (uterine malformation), uncontrolled chronic illness (diabetes, hypertension), or placental problems (placental abruption, placenta previa).

    Meanwhile, pregnancy loss after 20 weeks is considered a stillbirth. In this event, the baby will have died, and the mother will no longer feel any movement. More often than not, the woman will require a D&E rather than having to wait for the process to happen naturally

    Sources:

    Jurkovic, D. “Diagnosis and management of first trimester miscarriage.” BMJ.  2013; 346:f3676.

    Sneider, K.; Langhoff-Roos, J.; Sundhoff, I. et al. “Validation of second trimester miscarriages and spontaneous deliveries.” Clin Epidemiol. 2015; 7: 517–527.

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