During the second trimester of pregnancy (weeks 13 to 24), patients will continue to see their physician monthly. These prenatal care visits will focus on:

• Predicting the due date more accurately. The size of the woman’s uterus (womb), measured from the pubic bone to the top of the uterus in centimeters (cm), is called fundal height. The fundal height is an indicator of the baby’s age. The patient will be asked to empty her bladder before the fundal height is measured. The physician will then gently tap and press on the abdomen and measure along the front of the abdomen from that point to the patient’s pubic bone. At the middle of a patient’s pregnancy, the fundal height commonly equals the number of weeks the patient has been pregnant.
  
  
• Tracking the baby’s growth and health. The patient’s weight and blood pressure will be checked at every prenatal care visit. She will also be asked about any symptoms she may be experiencing. In addition, the physician will start checking the baby’s position, size and heart rate at this time using an ultrasound (sonogram) device.
  
  
• Assessing movement of the fetus. Patients often feel the baby move inside them by 20 weeks of pregnancy. Women should note the date they first notice fetal movement and report it to their physician at their next prenatal care visit. This date can help the physician predict the baby’s due date more accurately.
  
  
• Prenatal testing. Patients may be offered prenatal testing during the second trimester of pregnancy, which can identify genetic and congenital problems that may affect the developing baby. A physician who is aware of such problems ahead of time may be able to treat the condition more effectively or help prepare the parents for attending to the special needs of the baby. Prenatal tests may include:
  
  
• Alpha-fetoprotein (AFP) screening. Measures the level of the antigen AFP in the patient’s blood. This test can identify multiple fetuses, Down syndrome and other types of chromosome problems or neural tube defects such as spina bifida.
  
  
• Multiple marker screening. Measures specific hormones in the blood. This test can identify a fetus at risk for specific chromosomal abnormalities or birth defects.
  
  
• Amniocentesis. A sample of the amniotic fluid is removed and tested for certain fetal abnormalities, such as spina bifida or Down syndrome. Usually this procedure is recommended only for women over age 35 and those at increased risk of having a baby with one of these conditions.
  
  
• Screening for complications. Near the end of the patient’s second trimester, she will be screened for pregnancy complications such as gestational diabetes (diabetes that occurs only during pregnancy), Rh antibodies (antibodies that when present increase the baby’s risk of developing conditions such as anemia or jaundice following birth) and anemia (a condition characterized by a deficiency in red blood cells and low iron levels).
  
  The level of protein in the urine will also be measured. High protein levels can indicate preeclampsia (a dangerous condition characterized by high blood pressure and proteinuria [protein in the urine]).

Many changes take place during the second trimester of pregnancy. Therefore, it is imperative, for the sake of both the expectant mother and the developing baby, that patients notify their physician of any symptoms they may experience during this time. Patients may also want to begin asking questions about the upcoming childbirth and breastfeeding.