Updated November 25, 2014.

Question: What Causes Second Trimester Miscarriages?

 

Pregnancy loss in the second trimester can take women by surprise. As many people are aware, the majority of miscarriages happen in the first trimester, but the sad truth is that second-trimester pregnancy losses happen, too.

 

Answer:

Technically, a second-trimester miscarriage is a loss that happens between 12 and 20 weeks. A pregnancy loss after 20 weeks would be classified as a stillbirth or a neonatal death.

A number of factors can lead to second-trimester miscarriage. Some miscarriages diagnosed in early in the second trimester might have actually occurred in the first trimester but were not detected immediately (these would be called missed miscarriages).

Losses that occur after 12 weeks can be due to chromosomal abnormalities, which are a major culprit in almost all forms of pregnancy loss. But second-trimester miscarriages have a much greater likelihood than first-trimester miscarriages to be caused by other factors. Some of these are:

• Cervical insufficiency or very early preterm labor
• Infections
• Abdominal trauma
• Congenital birth defects, such as heart malformations in the baby
• Thrombophilia disorders
• Problems with the placenta (such as placental abruption)
• Unknown causes

Women who have had second-trimester pregnancy losses should consult with a doctor early in their next pregnancies in case extra monitoring is needed.

_Sources:

March of Dimes, "Miscarriage." June 2005. Accessed 15 Feb 2008.

Miscarriage Association, “Late Miscarriage.” Accessed 15 Feb 2008.