Which of the following are important nursing considerations related to fetal development in the third trimester (weeks 28-40)? Select all that apply.

Fetal renal development begins during week 5 of gestation with the formation of the metanephros, the permanent kidney. By week 9–12, the kidneys start producing urine, which is excreted into the amniotic cavity, making the kidneys a major contributor to amniotic fluid volume. Amniotic fluid, composed largely of fetal urine after the first trimester, is essential for lung development, fluid-electrolyte balance, and musculoskeletal movement. The fetal glomerular filtration rate (GFR) remains low compared to postnatal levels, and fetal kidneys do not filter maternal blood. Normal amniotic fluid index (AFI) ranges from 5 to 25 cm in the second and third trimesters.

Rationale for correct answers

B. By week 12, fetal kidneys begin producing urine, which is excreted into the amniotic sac. This urine significantly contributes to amniotic fluid volume, which is vital for normal fetal development, particularly pulmonary and musculoskeletal growth.

Rationale for incorrect answers

A. Red blood cells are produced by the yolk sac early in gestation, then by the liver and spleen. The fetal kidneys do not participate in hematopoiesis at any stage.

C. The fetal kidneys are immature and do not regulate systemic blood pressure effectively. Fetal blood pressure regulation is primarily under control of the placenta and fetal adrenal hormones, not the renal system.

D. Fetal kidneys do not filter maternal blood. Exchange of nutrients and waste products between mother and fetus occurs via the placenta, not through direct blood filtration by fetal organs.

Take home points

• Fetal kidneys begin producing urine by weeks 9–12.

• Urine becomes the main source of amniotic fluid after the first trimester.

• Amniotic fluid supports lung development and fetal movement.

• Fetal kidneys do not regulate blood pressure or filter maternal blood.

Third trimester nursing care (weeks 28–40) centers on fetal maturation, maternal readiness for delivery, and monitoring for complications like preterm labor or infections. At this stage, the fetus undergoes rapid brain growth, lung surfactant production, and weight gain, reaching approximately 3,000–3,500 grams by term. Nurses must ensure Rho(D) immune globulin (RhoGAM) is administered at 28 weeks for Rh-negative mothers to prevent alloimmunization. Group B Streptococcus (GBS) screening is performed between 36–37 weeks. Preterm labor signs include uterine contractions, pelvic pressure, and cervical changes before 37 weeks. Fetal kick count education is essential, with fewer than 10 movements in 2 hours considered abnormal.

Rationale for correct answers

A. RhoGAM is administered at 28 weeks to Rh-negative mothers to prevent maternal antibody formation against Rh-positive fetal red blood cells, which can lead to hemolytic disease in future pregnancies.

B. Monitoring for preterm labor is critical during the third trimester. Early recognition of signs like uterine contractions every 10 minutes or cervical dilation enhances neonatal outcomes through timely interventions.

D. GBS screening is recommended at 36–37 weeks to identify maternal colonization. If positive, intrapartum antibiotics reduce the risk of neonatal GBS sepsis.

E. Educating mothers about fetal movement monitoring helps detect fetal distress. A common method is counting at least 10 movements in 2 hours; decreased movement may signal hypoxia.

Rationale for incorrect answers

C. Folic acid supplementation is essential preconceptionally and during the first trimester to prevent neural tube defects, which occur by day 28 of gestation. It is not a primary focus in the third trimester.

Take home points

• RhoGAM is given at 28 weeks to Rh-negative mothers to prevent alloimmunization.

• GBS screening occurs at 36–37 weeks to prevent neonatal infection.

• Preterm labor signs require immediate attention before 37 weeks.

• Kick counts help assess fetal well-being in late pregnancy.