E2 – Early Pregnancy Complications
Miscarriage (spontaneous abortion)
- A natural (spontaneous) loss of a pregnancy (or a fetus) before it has reached a gestation of viability (after which pregnancy loss is classified as “stillbirth”).
- In Hong Kong, the cut-off gestation for fetal viability is 24 weeks.
- Some countries use 20 or 22 weeks gestation, or 500g as the cut-off.
- Miscarriage happens in 10-20% women.
- Most of them occur before 10 weeks of gestation.
- With growing gestation past the first trimester, the risk of miscarriage gradually drops.
- Causes of miscarriage:
- As early pregnancy loss (<10 weeks) are common, and the majority of them are due to sporadic chromosomal abnormalities, investigations are usually not necessary as the risk of recurrence is very low.
- However, further investigation may be indicated for the followings which are covered by other chapters:
- second trimester miscarriage, especially those initially present with rupture of membranes or painless cervical dilatation suggestive of cervical incompetence
- fetus with malformations
- recurrent miscarriage