Placental Calcification

Placental calcification is the deposit of calcium salts in the placenta, shown as bright echoes on ultrasound, and it is graded 0 to III by the pattern of the chorionic plate and basal plate. It increases with gestation and is normal near term. It matters when grade III appears before 36 weeks, because early calcification is linked with smoking, hypertension, growth restriction and placental insufficiency.

• Grade III before 36 weeks suggests premature ageing of the placenta.
• Risk factors: smoking, hypertension and preeclampsia, diabetes, high calcium or vitamin D intake, post term pregnancy.
• Isolated calcification at term needs no treatment.

Women have no symptoms. Examination is normal unless the cause is hypertension or growth restriction.

• Found at a growth scan or term scan.
• Fundal height may be small for dates if growth is restricted.
• Differential diagnosis: normal ageing of the placenta, placental infarction, intervillous thrombosis, chronic abruption, fibrin deposition, calcified chorioangioma.
• Complications: fetal growth restriction, oligohydramnios, preterm birth, stillbirth, intrapartum fetal distress.

The approach is to grade the placenta, with assessment of fetal growth and Doppler when it is early.

• Ultrasound: echogenic dots and lines in the placenta, grade 0 (smooth chorionic plate), I (subtle indentations), II (indentations reaching but not through to the basal plate), III (indentations reaching the basal plate with circular densities).
• Estimated fetal weight, amniotic fluid index, umbilical artery Doppler and cerebroplacental ratio when grade III appears before 36 weeks.
• Maternal blood pressure, urine protein, glucose, smoking history.
• Cardiotocography if reduced fetal movements.

The principle is no treatment for isolated calcification and surveillance of growth and wellbeing when it is early.

• Supportive: stop smoking and alcohol; normal activity; daily fetal movement counts; avoid excess calcium supplements.
• Pharmacological: aspirin 150 mg oral at night from 12 weeks to 36 weeks in the next pregnancy for women with a past history of early calcification with preeclampsia or growth restriction; labetalol 200 mg oral every 8 to 12 hours (maximum 2.4 g daily) or nifedipine modified release 30 to 60 mg oral once daily (maximum 120 mg) for blood pressure 140/90 mmHg or more; insulin or metformin 500 mg oral with meals increased to 1 g 12-hourly (maximum 2.5 g daily) for diabetes.
• Procedures: none; delivery at 39 to 40 weeks for isolated calcification, earlier for growth restriction, abnormal Doppler or pathological cardiotocography.
• Red flags: reduced fetal movements, falling growth centile, oligohydramnios, hypertension, abnormal Doppler.
• Follow-up: growth scan every 2 to 4 weeks when early; cardiotocography weekly from 36 weeks; antenatal review every 2 weeks.