Open Access Research article

Birth weight for gestational age norms for a large cohort of infants born to HIV-negative women in Botswana compared with norms for U.S.-born black infants

Lynn T Matthews12*, Heather J Ribaudo3, Natasha K Parekh4, Jennifer Y Chen5, Kelebogile Binda6, Anthony Ogwu6, Joseph Makhema6, Sajini Souda6, Shahin Lockman7, Max Essex8 and Roger L Shapiro1

Author Affiliations

1 Beth Israel Deaconess Medical Center, Division of Infectious Disease, 110 Francis Street, Lowry Medical Office Building - Suite GB, Boston, MA 02115, USA

2 Massachusetts General Hospital, Division of Infectious Disease, Center for Global Health, 100 Cambridge Street, Boston, MA, 02114, USA

3 Harvard School of Public Health, 651 Huntington Avenue, FXB Building - Room 509, Boston, MA 02115, USA

4 University of Miami, Miller School of Medicine, 1600 NW Tenth Avenue, Miami, FL 33136, USA

5 Harvard Medical School, 25 Shattuck Street, Boston, MA 02115, USA

6 Botswana Harvard AIDS Institute, Private Bag BO 320, Bontleng, Gaborone, Botswana

7 Brigham and Women's Hospital, Division of Infectious Disease, 75 Francis Street, Boston, MA 02115, USA

8 Harvard School of Public Health, Departments of Immunology and Infectious Disease, 651 Huntington Avenue, FXB Building - Room 401, Boston, MA 02115

For all author emails, please log on.

BMC Pediatrics 2011, 11:115  doi:10.1186/1471-2431-11-115

Published: 16 December 2011

Abstract

Background

Standard values for birth weight by gestational age are not available for sub-Saharan Africa, but are needed to evaluate incidence and risk factors for intrauterine growth retardation in settings where HIV, antiretrovirals, and other in utero exposures may impact birth outcomes.

Methods

Birth weight data were collected from six hospitals in Botswana. Infants born to HIV-negative women between 26-44 weeks gestation were analyzed to construct birth weight for gestational age charts. These data were compared with published norms for black infants in the United States.

Results

During a 29 month period from 2007-2010, birth records were reviewed in real-time from 6 hospitals and clinics in Botswana. Of these, 11,753 live infants born to HIV-negative women were included in the analysis. The median gestational age at birth was 39 weeks (1st quartile 38, 3rd quartile 40 weeks), and the median birth weight was 3100 grams (1st quartile 2800, 3rd quartile 3400 grams). We constructed estimated percentile curves for birth weight by gestational age which demonstrate increasing slope during the third trimester and leveling off beyond 40 weeks. Compared with black infants in the United States, Botswana-born infants had lower median birth weight for gestational age from weeks 37 through 42 (p < .02).

Conclusions

We present birth weight for gestational age norms for Botswana, which are lower at term than norms for black infants in the United States. These findings suggest the importance of regional birth weight norms to identify and define risk factors for higher risk births. These data serve as a reference for Botswana, may apply to southern Africa, and may help to identify infants at risk for perinatal complications and inform comparisons among infants exposed to HIV and antiretrovirals in utero.