title: Maternal complications following amniocentesis and chorionic villus sampling for prenatal karyotyping.
abstract: OBJECTIVE
  To investigate whether amniocentesis and chorionic villus sampling increase the risk of bleeding, placental abruption, complications related to amniotic cavity and membranes, abnormal labour, operative deliveries and to investigate the impact of gestational length at the time of the procedure.
  
  
  METHODS
  A population-based cohort study.
  
  
  METHODS
  Sweden, 1991-1996.
  
  
  METHODS
  All women, 35 to 49 years old, with single births (N = 71,586). The women were classified as exposed to amniocentesis (N = 21,748) or chorionic villus sampling (N = 1984) or not exposed (N = 47,854).
  
  
  METHODS
  Maternal outcomes were collected from the Swedish Medical Birth Register and the Swedish Hospital Discharge Register. With Logistic regression analyses odds ratios were calculated.
  
  
  METHODS
  Crude and adjusted odds ratios of bleeding, complications related to amniotic cavity and membranes, abnormal labour and operative deliveries. Women exposed to amniocentesis or chorionic villus sampling were compared with women non-exposed.
  
  
  RESULTS
  Neither amniocentesis nor chorionic villus sampling was associated with severe pregnancy complications such as placental abruption or placenta praevia. Women in the amniocentesis group had a lower chance of normal delivery (OR = 0.93, 95% CI 0.90-0.97), an increased risk of complications related to amniotic cavity and membranes (OR = 1.15, 95% CI 1.06-1.24) and hypotonic uterine dysfunction (OR = 1.12, 95% CI 1.06-1.18). The risks were higher for amniocentesis before 15 weeks of gestation. Women in the amniocentesis group were more often delivered by forceps or vacuum extractions (OR = 1.11, 95% CI 1.03-1.19) and elective caesarean sections (OR = 1.09, 95% CI 1.02-1.16). For the chorionic villus sampling group, no significant associations were found.
  
  
  CONCLUSIONS
  Among women aged 35-49 years, amniocentesis is not associated with important adverse outcomes such as abruption or placenta praevia. Minor associations were found for other maternal complications when amniocentesis was performed before 15 weeks of gestation. Improved methods to identify women with increased risk of chromosomally abnormal pregnancies might minimise the number of women exposed to invasive procedures.
authors.affiliation: Section of Obstetrics and Gynaecology, Department of Women's and Children's Health, Uppsala University, Sweden.
authors.forename: Maria
authors.initials: M
authors.lastname: Cederholm
authors.forename: Bengt
authors.initials: B
authors.lastname: Haglund
authors.forename: Ove
authors.initials: O
authors.lastname: Axelsson
mesh_terms: D000037:Abruptio Placentae / Q000209:etiology*; D000328:Adult; D000649:Amniocentesis / Q000009:adverse effects*; D015992:Body Mass Index; D015193:Chorionic Villi Sampling / Q000009:adverse effects*; D015331:Cohort Studies; D005260:Female; D006470:Hemorrhage / Q000209:etiology*; D006801:Humans; D007621:Karyotyping; D016015:Logistic Models; D008875:Middle Aged; D011247:Pregnancy; D011249:Pregnancy Complications, Cardiovascular / Q000209:etiology*; D012044:Regression Analysis