Fetal heart
Question 1—Third Trimester
Fetal growth is an important part of fetal assessment in the third trimester. Studies show that poor fetal growth in the second and third trimesters are associated with increased risks of preterm birth, low birthweight, and long-term adverse health outcomes (Gaillard, Steegers, de Jongste, Hofman, & Jaddoe, 2014). Fundal height is often used to assess fetal growth. If fundal height differs by 3 cm or more from gestational age, a follow-up ultrasound is advised to assess further (McCowan, Figueras, & Anderson, 2018).
Fetal heart rate and fetal activity should also be routinely assessed. The mother should be asked about fetal activity. Counting the kicks should be highly encouraged starting at week 28 (Bryant & Thistle, 2019). A kick count of less than 10 in 2 hours may be cause for concern (Bryant & Thistle, 2019). Fetal heart rate should also be assessed at every prenatal visit in the third trimester (ACOG, 2018). A typical fetal heart rate is between 120 and 160 beats per minute. Changes in fetal activity or fetal heart rate indicate a need for further testing. A non-stress test and/or a biophysical profile (BPP) may be ordered when results are nonreassuring (ACOG, 2018). A biophysical profile is an ultrasound that assesses: fetal breathing movement, fetal movement of the body or limbs, fetal tone and amniotic fluid volume (Bryant & Thistle, 2019).
Maternal blood pressure, urinalysis, and degree of edema are also important measurements that can affect the health of the fetus (Zolotor & Carlough, 2014). Blood pressure measurements can help identify chronic hypertension or hypertensive disorders that develop during pregnancy, such as preeclampsia or gestational hypertension (Zolotor & Carlough, 2014). Edema may be a normal finding but can also be a sign of preeclampsia (Zolotor & Carlough, 2014). Protein in the urine may also indicate preeclampsia risk (Zolotor & Carlough, 2014). These findings may also suggest the need for blood tests, fetal ultrasounds, nonstress tests, or a BPP (Zolotor & Carlough, 2014).
Lastly, fetal presentation is encouraged to be assessed beginning at 36 weeks gestation (Zolotor & Carlough, 2014). This is most often done using the Leopold maneuvers (Zolotor & Carlough, 2014). External cephalic version may be used to turn a fetus from a breech or transverse position into a vertex position before birth (Zolotor & Carlough, 2014).
References
ACOG. (2018). Special tests for monitoring fetal health. Retrieved from https://www.acog.org/Patients/FAQs/Special-Tests-for-Monitoring-Fetal-Health?IsMobileSet=false#exam
Bryant, J. & Thistle, J. (2019). Fetal movement. Treasure Island, FL: StatPearls Publishing. Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK470566/
Gaillard, R., Steegers, E. A., de Jongste, J. C., Hofman, A., & Jaddoe, V. W. (2014). Tracking of fetal growth characteristics during different trimesters and the risks of adverse birth outcomes. International Journal of Epidemiology, 43(4), 1140-1153. https://dx.doi.org/10.1093%2Fije%2Fdyu036
McCown, L., Figueras, F., & Anderson, N. (2018). Evidence-based national guidelines for the management of suspected fetal growth restriction: Comparison, consensus, and controversy. American Journal of Obstetrics & Gynecology, 218(2),855–868. doi: 10.1016/j.ajog.2017.12.004.
