In a pregnant woman with short stature (<150 cm), what are the obstetric risks and recommended management?

Short Stature in Pregnancy: Obstetric Risks and Management

Pregnant women with height <150 cm require heightened surveillance for cephalopelvic disproportion and should be counseled about increased cesarean delivery rates, but routine cesarean section is not indicated based on height alone. 1, 2

Key Obstetric Risks

Cesarean Delivery Risk

• Women <150 cm have 2-3 times higher cesarean section rates compared to women of average height, with rates ranging from 35-43% in very short women (122-136 cm) versus 23% in controls. 3, 4
• The primary indication is cephalopelvic disproportion (CPD), though maternal height alone does not mandate cesarean delivery. 2, 5
• Age extremes compound the risk: women <150 cm who are either <19 years or >39 years have significantly higher cesarean rates than short women of intermediate age. 2

Fetal and Neonatal Outcomes

• Infants born to mothers <150 cm have lower mean birth weights (approximately 2,928 g vs 3,068 g in controls) and higher rates of low birth weight (<2,500 g: 10.9% vs 3.2%). 5
• Increased prevalence of intrauterine growth restriction, intrauterine asphyxia, and lower Apgar scores despite increased obstetric intervention. 3
• These outcomes persist even with active labor management, indicating intrinsic risk beyond mechanical factors. 3

Labor Complications

• Short stature is associated with obstructed labor due to CPD, though this risk varies by population and ethnicity. 1
• In some populations, up to 54% of cesarean sections occur in the 4% of women <150 cm. 1

Recommended Management Approach

Preconception and Early Pregnancy

• Preconception counseling should address increased cesarean risk and potential for CPD. 6
• Ensure accurate pregnancy dating using first-trimester crown-rump length to properly assess fetal growth. 7
• Consider low-dose aspirin (100-150 mg daily) before 16 weeks if additional risk factors for placental insufficiency are present. 7

Antenatal Surveillance

• Serial growth ultrasounds starting at 28-32 weeks to monitor for fetal growth restriction, as standard fundal height measurements may be less reliable. 6, 7
• Umbilical artery Doppler assessment if fetal growth restriction is suspected (EFW <10th percentile). 8, 7
• Monitor for signs of intrauterine asphyxia given the increased baseline risk. 3

Delivery Planning

• Early discussion of delivery mode (ideally by second trimester) including location, anesthetic options, and neonatal care availability. 6
• Height <150 cm alone does not mandate cesarean delivery; trial of labor is reasonable in the absence of other contraindications. 2, 5
• Plan for continuous electronic fetal monitoring during labor given increased risk of fetal compromise. 8
• Have cesarean capability immediately available, as the risk of intrapartum CPD is elevated. 3, 4

Anesthetic Considerations

• Preconception or early pregnancy anesthesia consultation is recommended to assess airway, cardiopulmonary status, and neuraxial anatomy. 6
• Anatomical differences may increase risks of both general and regional anesthesia. 6
• Careful fluid management is required; adjust IV fluid volumes proportionate to patient size to avoid fluid overload (do not use standard 1 L preloading before epidural). 6

Critical Clinical Pitfalls

• Do not assume all short women require cesarean delivery: the majority can deliver vaginally, particularly if maternal age is 19-39 years. 2, 5
• Do not overlook population-specific risk: the cut-off height for "at risk" designation should consider the distribution of maternal height in your specific population. 1
• Do not delay intervention for intrauterine asphyxia: short stature is associated with higher rates of fetal compromise despite active management. 3
• Do not use standard fluid protocols: women of short stature have proportionally smaller volume of distribution and are at risk for fluid overload with standard peripartum IV fluid regimens. 6

Special Considerations for Skeletal Dysplasia

If short stature is due to skeletal dysplasia (rather than constitutional short stature), additional considerations apply:

• Cesarean delivery is recommended in most cases due to pelvic anatomy that precludes vaginal delivery. 6
• Women with short-trunk skeletal dysplasia require vigilance for cardiopulmonary complications as fundal height increases. 6
• Standard weight gain recommendations do not apply; BMI-based guidelines are problematic when body proportions are abnormal. 6
• Preterm delivery may be necessary before term despite absence of preterm labor, due to maternal cardiopulmonary or musculoskeletal compromise. 6