Static symphysis-fundal height at 28 weeks in a smoker with limited transport
Amara is 31 years old, G3P1 (one term vaginal birth, one first-trimester miscarriage), and booked at 12 weeks with a BMI of 31.2. She smokes 12 cigarettes a day and has a carbon monoxide reading of 9 ppm. At 28+4 weeks she attends the community clinic. Her symphysis-fundal height is 23 cm; it was 25 cm at 24 weeks. The customised growth chart plots the measurement below the 10th centile. Blood pressure is 118/72 mmHg, urine dipstick is negative for protein, and the fetal heart is heard at 144 beats/min with a handheld Doppler. Amara reports normal fetal movements. She has a 4-year-old at school, no car, and the hospital is 45 minutes away by bus; the clinic is 15 minutes from home. She is anxious because a friend was ‘talked into an induction’ and says she wants to avoid one ‘at all costs’.
1. How do you interpret the symphysis-fundal height finding, and what is your immediate plan? Explain your reasoning, including what you would not do.
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Interpretation
- A symphysis-fundal height that has fallen from 25 cm to 23 cm and plots below the 10th centile on a customised chart is a red flag for fetal growth restriction. The static or falling measurement matters more than the absolute number.
- Risk factors in this history include smoking, BMI over 30, and a previous pregnancy; I would also ask the birth weight of her first baby, because a previous small-for-gestational-age infant raises recurrence risk.
- A normal handheld Doppler rate does not exclude growth restriction or placental insufficiency. Auscultation confirms a heartbeat, not fetal wellbeing.
Immediate plan
- Arrange an ultrasound scan for estimated fetal weight and amniotic fluid volume, usually within 72 hours, and explain why it is needed.
- Check blood pressure and urine again, ask specifically about reduced movements, headache, visual disturbance, and epigastric pain.
- Review whether she was offered low-dose aspirin from 12 weeks for her risk factors; if not, discuss it now, although it will not alter this measurement.
- Document the measurement, the customised chart plot, the conversation, and the scan request. Contact the ultrasound department and, if the scan is abnormal, refer to the obstetric team.
- Give clear safety-netting advice: if movements reduce, she should contact the maternity unit immediately, not wait for the scan.
What I would not do
- I would not reassure her on the basis of the Doppler alone.
- I would not recommend immediate induction before the scan and clinical review; the decision depends on growth, liquor volume, Doppler findings, and gestational age.
- I would not suggest a home Doppler device.
2. Amara asks whether she can wait until 40 weeks and have a home birth. Using the findings so far, how would you counsel her and document the discussion?
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I would start by acknowledging that her preference is important and that many women want to avoid unnecessary intervention. I would then explain that the current measurement is a screening signal, not a diagnosis, and that the scan will tell us whether the baby is growing normally.
Counselling points
- If the scan and any Doppler studies are normal, she may remain in a lower-risk category, and place of birth can be discussed again. A normal scan does not guarantee a normal outcome, but it changes the risk estimate.
- If the scan shows growth restriction, reduced liquor, or abnormal Doppler, the balance shifts towards birth in an obstetric unit with continuous monitoring and consultant involvement. Induction may be recommended before 40 weeks because the risk of stillbirth increases with growth restriction.
- I would explain that induction is a recommendation, not a procedure that can be imposed; she can ask about expectant management, but she needs to understand the uncertainties and the monitoring that would be required.
- I would ask her to bring her partner or a friend to the next appointment if she wants support with the decision.
Documentation I would record the scan request, the risks and benefits discussed, her stated preference for home birth, her understanding that this may change, and that the plan will be reviewed after the scan. I would involve the consultant midwife or obstetric team early rather than waiting until 36 weeks.