Fetal Abdominal Subcutaneous Fat Thickness as a Predictor of Low Birth Weight in Term Pregnancy

Abstract

Objective :To study  whether  fetal  abdominal  fat  can  predict  fetal  low  birth weight in term pregnancy.

Study design :Descriptive diagnostic test study

Setting :  Labor room, Srinagarind  Hospital, Faculty of Medicine, Khon Kaen University.

Subjects :Three  hundred  twenty  eight  term  pregnant women with singleton pregnancies who were admitted  for  delivery  at  Sriganarind  hospital  between  September 1, 2000 to July 30, 2001.

Methods :Term  pregnant women  were examined  by  ultrasound. Fetal  abdominal  fat  thickness   was   measured   using   the  same   plane as  the abdominal circumference.

Main  outcome measures : Fetal abdominal  fat  thickness  in  millimeters  and  birth  weight in grams.

Results :Three   hundred  and  five   fetuses  were  normal   birth   weight ,  10  were  low   birth weight (weight < 2,500 g), and 13  were  macrosomia   (weight > 4,000 g). The incidence of  low  birth  weight  in  this  study  was  3.0% . The fetal abdominal fat thickness ranged between  2.8 - 6.3  mm  in  all  fetuses,  with   a   mean  of  4.2  + 0.56  mm . There  was  a significant  positive  correlation  between   the   abdominal   fat    thickness  and   the   birth   weight   (r = 0.512 , p < 0.0005). Infant  with  abdominal  fat  thickness  less  than  or  equal 4 mm  were  more  likely  to have low  birth weight. The  diagnostic  performance  of  this method was: a sensitivity of  90.0%  (95%CI=86.8-93.3), a  specificity  of  53.5%  (95% CI=48.1-58.9),  a  positive  predictive  value  of  5.7%  (95% CI=3.2-8.3)  and    negative   predictive   value  of  99.4%  (95% CI=98.6-100.0)

Conclusion :Sonographic  measurement  of   the fetal abdominal fat thickness less than  or equal

4  mm  may  be  useful  for  screening  of  low  birth  weight  infant.

Key words : fetal abdominal fat thickness, low birth weight