- Maternal progesterone is higher and rises linearly in normal pregnancies.
Why this matters
- Threatened abortion affects 15%-20% of all pregnancies.
- Threatened abortion is a risk factor for future pregnancy complications including miscarriage, preeclampsia, preterm delivery, and preterm premature rupture of membranes.
- Miscarriage rate was 5.4% in the normal pregnancy group and 21.5% in the threatened abortion group (P<.0001>
- Mean serum progesterone was higher in the normal pregnancy group compared with the threatened abortion group (71.8 vs 53.6 nmol/L; P<.0001>
- Serum progesterone increased linearly from 5 to 13 weeks in the normal pregnancy group.
- Median progesterone was uniformly lower in the threatened abortion group converging with the normal group by 13 weeks.
- Women with spontaneous miscarriage showed a marginal and nonsignificant increase in serum progesterone.
- Prospective cohort study (n=929).
- Normal pregnancies were recruited from antenatal clinics (n=450); women with threatened abortion (vaginal bleeding with normal sonographic findings between 5 and 13 weeks) were recruited from emergency walk-in clinics (n=479).
- Maternal blood samples were taken to assess progesterone levels.
- Funding: Ministry of Health Industry Alignment Fund Category 1 research fund.
- Distribution of serum progesterone across gestations does not represent samples from the same patient.