From the Guidelines
A threatened miscarriage should be evaluated immediately by a healthcare provider, with treatment focusing on rest, avoiding strenuous activities, and close monitoring with ultrasounds and hormone levels to assess viability, as evidenced by the recent consensus conference recommendations 1. When a patient presents with a threatened miscarriage, it is essential to perform a transvaginal ultrasound (TVUS) to assess the pregnancy and determine the best course of action. According to the Society of Radiologists in Ultrasound consensus conference recommendations 1, the TVUS criteria for concerning for early pregnancy loss (EPL) include an embryonic crown-rump length (CRL) <7 mm and no cardiac activity, or a mean sac diameter (MSD) of 16-24 mm and no embryo.
- Key points to consider in the management of threatened miscarriage include:
- Rest and avoiding strenuous activities to reduce the risk of progression to actual miscarriage
- Abstaining from sexual intercourse until symptoms resolve
- Close monitoring with ultrasounds and hormone levels to assess viability
- Psychological support during this stressful time, as about 50% of threatened miscarriages progress to actual miscarriage, often due to chromosomal abnormalities that cannot be prevented 1
- Seeking immediate medical attention if bleeding increases, severe pain develops, or tissue is passed, as these may indicate progression to an inevitable miscarriage It is crucial to note that there is no proven medication to prevent miscarriage in these cases, and progesterone supplementation may be offered in some cases, though evidence for its effectiveness is mixed 1. Bed rest is no longer routinely recommended as it hasn't been shown to improve outcomes.
From the Research
Definition and Risk Factors
- Threatened miscarriage is a common complication of pregnancy, occurring in about 20% of recognised pregnancies 2
- Risk factors for miscarriage include older age, history of miscarriage, low serum levels of progesterone or human chorionic gonadotrophin (hCG), heavy bleeding, early gestational age, and an empty gestational sac of >15-17 mm diameter 2
Treatment Options
- Bed rest is the most common choice of treatment, but there is little evidence of its value 2
- Other options include luteal support with progesterone, dydrogesterone, or hCG 2
- Progesterone or dydrogesterone may reduce the rate of miscarriage, but further data from double-blind, randomised-controlled trials are necessary to confirm efficacy 2
Efficacy of Progesterone
- A randomized, double-blinded, placebo-controlled trial found that 400 mg vaginal progesterone nightly did not increase live birth rates in women with threatened miscarriage 3
- A meta-analysis of randomized controlled trials found that progesterone supplementation had a relationship with a reduction in the rate of miscarriage, but did not significantly improve the incidence of preterm and live birth 4
- Another study found that dydrogesterone was associated with a lower risk of miscarriage compared to natural progesterone, and oral management was demonstrated to have a lower risk of miscarriage compared to vaginal administration 5
Comparison of Progestogens
- A network meta-analysis found that oral dydrogesterone can reduce the risk of miscarriage compared to both placebo and vaginal progesterone in women with first threatened miscarriage 6
- Oral progesterone also reduced the risk of miscarriage compared to placebo, but there was no statistically significant difference between progestogens and placebo in preterm birth, congenital abnormality, and live birth rate 6
Key Findings
- Progesterone supplementation may reduce the rate of miscarriage in women with threatened miscarriage, but the evidence is not conclusive 2, 3, 5, 4, 6
- Different types of progestogens, such as dydrogesterone and progesterone, may have different effects on miscarriage rates 5, 6
- Further research is needed to determine the efficacy and safety of progestogens in women with threatened miscarriage 2, 3, 5, 4, 6