We have studied a large population-based cohort of women who had amniocentesis at 14 weeks' gestation (early amniocentesis) in Victoria, a state of Australia, to determine fetal loss rates and maternal morbidity. This was done by linking two registers-one containing information on all prenatal diagnostic tests in the state, and the other a register of all births at or after 20 weeks' gestation. Almost complete follow-up was achieved. The spontaneous fetal loss rate was significantly higher for women of age 37 years and over having early amniocentesis (2β’5 per cent), as compared with the fetal loss rate found previously on the same geographically defined population who had amniocentesis at about 16 weeks' gestational age (1β’1 per cent).
Three classes of maternal morbidity reported to the birth register (post 20 weeks' gestation) were also analysed. The most significant finding was a reduced rate of premature rupture of membranes with early amniocentesis when compared with a group having later amniocentesis, or the background population not having any amniocentesis. There was no significant increase in the occurrence of antepartum bleeding or genito-urinary tract infection for women having early amniocentesis. These data agree with other studies in showing that early amniocentesis is associated with a significant increased risk of fetal loss, as compared with later amniocentesis. In addition we have shown no significant increase in the occurrence of three indicators of maternal morbidity, reported at or after 20 weeks ' gestation. 1998 John Wiley & Sons, Ltd.