Background: The incidence of preterm meconium staining of the amniotic fluid (MSAF) is uncertain. It may be an indicator of possible listeriosis. It is unclear how great this risk is or whether preterm MSAF is a risk factor for adverse neonatal outcome.
Objective: To investigate the incidence of preterm MSAF, the incidence of associated maternal and neonatal infection, and the outcomes of the infants at discharge.
Design: Retrospective case-control study.
Methods: Infants < 33 weeks gestation with preterm MSAF born in the Simpson Memorial Maternity Pavilion, Edinburgh between 1 January 1994 and 2 January 2001 were matched with the next infant of the same sex and gestation with clear liquor. Maternal and infant characteristics, culture results, placental histology, and clinical outcomes were compared.
Results: Preterm MSAF was observed in 45/1054 (4.3%) infants below 33 weeks gestation. No maternal or infant listeriosis was identified in cases or controls. There was no significant difference in birth weight, Apgar score, or first pH between cases and controls. Preterm MSAF was associated with prolonged rupture of the membranes (odds ratio (OR) 3.34, 95% confidence interval (CI) 1.07 to 10.49), but not maternal hypertension, sepsis, or chorioamnionitis. Severe (grade 3/4) intraventricular haemorrhage was significantly more common in infants with preterm MSAF (OR 2.03, 95% CI 1.62 to 2.53). There was no significant difference in mortality. Early onset sepsis was observed in two cases and three controls.
Conclusions: Preterm meconium staining of the amniotic fluid may be associated with increased risk of intraventricular haemorrhage. It does not appear to be a useful indicator of listeriosis.