The Second Trimester of Pregnancy: An Overview

Your Prenatal Visits

During the second trimester, monthly prenatal visits will continue until the midway point of your pregnancy—about 20 weeks. After 20 weeks, visits may be scheduled every two to three weeks or so. High-risk conditions such as preeclampsia or gestational diabetes, which require closer observation by your caregiver, may make these visits more frequent.

Here's a checklist of what to expect during your second trimester visits:

• Office visits are initially every three to four weeks, going to every two to three weeks in the second half of this trimester. Visits will be much like the routine visits of the first trimester.



• Your obstetrician or nurse midwife will listen for fetal heart tones and assess them for the expected rate and rhythm that indicates fetal well-being.



• The size of the baby is estimated and compared to the sizes recorded on previous visits to assure appropriate interval growth. Fundal height—a measurement from your pubic bone to the top of your uterus—is the measurement recorded each visit.



• You'll have an ultrasound to determine that you are carrying only a single baby versus twins (or more!).



• Between 15 and 20 weeks, you'll be offered an elective test called an alphafetoprotein (AFP) screen.



• Any minor complaints are addressed, and your caregiver should be especially sensitive to what might be a major problem presenting as a minor complaint.



• If you have a history of second-trimester miscarriage because your cervix is weak, you will be offered a cervical cerclage (a closing noose surgically placed around the cervix). The optimal time for this is 14 weeks if there is a threat of incompetent cervix.



• Your provider will do routine lab work, with monitoring to check for anemia, urinary tract infections, or warnings of pregnancy-related illnesses. These illnesses include, for example, toxemia (first renamed "preeclampsia," later called "pregnancy-induced hypertension," and sometimes "gestational hypertension").



• Between weeks 15 and 20, you and your partner can begin prenatal classes at the hospital or by private instruction.



• Between weeks 18 and 20, you may also be able to find out the gender of your baby-to-be in an office ultrasound.

Viability, Measurement, and Growth

It used to be that 28 weeks was considered the "time of viability," meaning the gestational milestone after which a premature baby could survive. With the advent of neonatal ICUs, however, this time has been whittled down. Currently, 25-week babies are entertained as survivable. Younger than that would put a baby into second-trimester territory, but this is a zone that is hard to cross when talking about a baby surviving in the outside world.