From the Guidelines
The risk of miscarriage is approximately 20% and may be increased by 7% in women with diminished ovarian reserve, although the evidence is not strong and has several limitations.
Risk Factors for Miscarriage
- Diminished ovarian reserve: Studies have shown a potential association between diminished ovarian reserve (DOR) and higher risk of miscarriage, with an odds ratio of 1.35, indicating a 35% relative increase in miscarriage rate 1.
- Age: Female age is the most reliable predictor of miscarriage, and may act as a possible effect modifier, limiting the strength of evidence 1.
- Other factors: Endometriosis and tubal factor infertility may also impact miscarriage rate, although the evidence is limited 1.
Evidence Limitations
- Study quality: The quality of available evidence is between low and very low when evaluated according to the GRADE system 1.
- Population: The studies were performed on an ART population, and the results may not be applicable to other populations 1.
- Confounding factors: The studies may not have controlled for confounding factors and effect modifiers, which could impact the results 1.
Clinical Implications
- Preconception counseling: The association between DOR and increased risk of miscarriage may guide future research and preconception counseling 1.
- Exercise during pregnancy: Regular physical activity within guidelines may benefit factors that increase the risk of miscarriage, such as insulin resistance and obesity, and improve general maternal health 1.
From the Research
Risk of Miscarriage
The risk of miscarriage is a significant concern for many women, with approximately 25% of women experiencing a miscarriage in their lifetime 2. This can be defined as the spontaneous loss of a pregnancy before 24 weeks' gestation.
Prevalence of Miscarriage
- Around 10 to 15% of all pregnancies end in early spontaneous first trimester miscarriage 3.
- Miscarriage occurs in one in five pregnancies 4.
- An estimated 15% of pregnancies end in miscarriage 2.
Risk Factors for Miscarriage
- Advancing maternal and paternal age are known to be associated with increasing chance of miscarriage 3.
- Being underweight or overweight, smoking, and high alcohol consumption are also risk factors 3.
- Low serum levels of progesterone or human chorionic gonadotrophin (hCG) are a risk factor for miscarriage 5.
- Heavy bleeding, early gestational age, and an empty gestational sac of >15-17 mm diameter are also risk factors 5.
- Infections such as malaria, brucellosis, cytomegalovirus, and human immunodeficiency virus can increase the risk of miscarriage 4.
- Higher age (>33 years), lower body mass index (< or =20 kg/m(2)), and lower serum progesterone concentrations (< or =12 ng/ml) prior to the onset of the miscarriage can increase the risk of miscarriage 6.
Management of Miscarriage
- Expectant management is the first-line approach, and is encouraged for 7-14 days after diagnosis of miscarriage 3.
- Medical management of miscarriage can be offered using misoprostol 3.
- Surgical management may be chosen by a woman if she has had a previous adverse or traumatic experience associated with pregnancy 3.
- All surgical and medical methods for managing a miscarriage may be more effective than expectant management or placebo 2.