title: Gestational age assessment in malaria pregnancy cohorts: a prospective ultrasound demonstration project in Malawi.
abstract: BACKGROUND
  Malaria during pregnancy is associated with an increased risk for low birth weight (<2500 grams). Distinguishing infants that are born premature (< 37 weeks) from those that are growth-restricted (less than the 10th percentile at birth) requires accurate assessment of gestational age. Where ultrasound is accessible, sonographic confirmation of gestational age is more accurate than menstrual dating. The goal was to pilot the feasibility and utility of adding ultrasound to an observational pregnancy malaria cohort.
  
  
  METHODS
  In July 2009, research staff (three mid-level clinical providers, one nurse) from The Blantyre Malaria Project underwent an intensive one-week ultrasound training to perform foetal biometry. Following an additional four months of practice and remote image review, subjects from an ongoing cohort were recruited for ultrasound to determine gestational age. Gestational age at delivery established by ultrasound was compared with postnatal gestational age assessment (Ballard examination).
  
  
  RESULTS
  One hundred and seventy-eight women were enrolled. The majority of images were of good quality (94.3%, 509/540) although a learning curve was apparent with 17.5% (24/135) images of unacceptable quality in the first 25% of scans. Ultrasound was used to date 13% of the pregnancies when menstrual dates were unknown and changed the estimated gestational age for an additional 25%. There was poor agreement between the gestational age at delivery as established by the ultrasound protocol compared to that determined by the Ballard examination (bias 0.8 weeks, limits of agreement -3.5 weeks to 5.1 weeks). The distribution of gestational ages by Ballard suggested a clustering of gestational age around the mean with 87% of the values falling between 39 and 41 weeks. The distribution of gestational age by ultrasound confirmed menstrual dates was more typical. Using ultrasound confirmed dates as the gold standard, 78.5% of preterm infants were misclassified as term and 26.8% of small-for gestational age infants misclassified as appropriately grown by Ballard.
  
  
  CONCLUSIONS
  Ultrasound should be strongly considered in prospective malaria studies with obstetric endpoints to confirm gestational age and avoid misclassification of infants as premature or growth-restricted. The use of ultrasound does require a significant investment of time to maintain quality image acquisition.
authors.affiliation: Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114, USA. bwylie@partners.org
authors.forename: Blair J
authors.initials: BJ
authors.lastname: Wylie
authors.forename: Linda
authors.initials: L
authors.lastname: Kalilani-Phiri
authors.forename: Mwayi
authors.initials: M
authors.lastname: Madanitsa
authors.forename: Gladys
authors.initials: G
authors.lastname: Membe
authors.forename: Osward
authors.initials: O
authors.lastname: Nyirenda
authors.forename: Patricia
authors.initials: P
authors.lastname: Mawindo
authors.forename: Redson
authors.initials: R
authors.lastname: Kuyenda
authors.forename: Albert
authors.initials: A
authors.lastname: Malenga
authors.forename: Abbey
authors.initials: A
authors.lastname: Masonbrink
authors.forename: Bonus
authors.initials: B
authors.lastname: Makanani
authors.forename: Phillip
authors.initials: P
authors.lastname: Thesing
authors.forename: Miriam K
authors.initials: MK
authors.lastname: Laufer
mesh_terms: D000886:Anthropometry / Q000379:methods*; D015331:Cohort Studies; D005260:Female; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D008288:Malaria / Q000473:pathology*; D008295:Malawi; D011247:Pregnancy; D011248:Pregnancy Complications / Q000473:pathology*; D011446:Prospective Studies; D014463:Ultrasonography / Q000379:methods*