If you have bleeding in mid-pregnancy, preterm labor must be one of the things that you are concerned about. However, a new study says that while you're still at risk of preterm labor, one tool they can use, measuring the length of your cervix, will not be beneficial.
"Pregnancies with vaginal bleeding are at risk for preterm birth but do not appear to undergo progressive cervical shortening. This suggests that women with vaginal bleeding undergo a different mechanism leading to preterm birth." Unfortunately, we're not sure what that means.
As for cervical shortening, if you have cervical shortening, you're at a 20% increased risk of preterm birth "for each additional millimeter per week increase in cervical slope. " Your doctor or midwife will talk to you about what this means and how best to treat it.
Behrendt, N, Gibbs, RS, Lynch, A, Hart, J, West, N, & Iams, JD. (2013). Rate of Change in Cervical Length in Women With Vaginal Bleeding During Pregnancy. Obstetrics & Gynecology, 121(2), 260-264. doi: 10.1097/AOG.0b013e31827d8e1b