Routine ultrasound in late pregnancy (after 24 weeks' gestation)

Ultrasound can be used in late pregnancy to assess the baby's condition when there are complications, but carrying out scans on all women is controversial. Scans can be used in late pregnancy to detect problems which may not otherwise be apparent, such as abnormalities in the placenta, in the fluid surrounding the baby, or in the baby's growth. If such problems are identified this may lead to changes in care and improved outcome for babies. At the same time, screening all women may mean that interventions are increased without benefit to mothers or babies. Scans are popular, but women may not fully understand the purpose of their scan and may be either falsely reassured or unprepared for adverse findings. Based on existing evidence, routine ultrasound, after 24 weeks gestation, in low-risk or unselected women does not provide any benefit for mother or baby. Eight studies that randomised 27,024 women to screening or a control group (no or selective ultrasound, or ultrasound with concealed results) contributed to the review. The quality of trials was satisfactory. There were no differences between groups in the rates of women having additional scans, antenatal admissions, preterm delivery, induction of labour, or instrumental deliveries although the rate of caesarean section increased slightly with screening. For babies, birthweight, condition at birth, interventions such as resuscitation, and admission to special care were similar between groups. Infant survival, with or without congenital abnormalities, was no different with and without routine screening, and childhood development at eight to nine years was similar in the three trials that measured it. None of the trials reported on psychological effects for mothers of routine ultrasound in late pregnancy.