Low Gestational Weight Gain and Risk of Adverse Perinatal Outcomes in Obese and Severely Obese Women.
BACKGROUND
Our objective was to estimate associations between gestational weight gain z scores and preterm birth, neonatal intensive care unit admission, large- and small-for-gestational age birth, and cesarean delivery among grades 1, 2, and 3 obese women.


METHODS
We included singleton infants born in Pennsylvania (2003-2011) to grade 1 (body mass index 30-34.9 kg/m, n = 148,335), grade 2 (35-39.9 kg/m, n = 72,032), or grade 3 (≥40 kg/m, n = 47,494) obese mothers. Total pregnancy weight gain (kg) was converted to gestational age-standardized z scores. Multivariable Poisson regression models stratified by obesity grade were used to estimate associations between z scores and outcomes. A probabilistic bias analysis, informed by an internal validation study, evaluated the impact of body mass index and weight gain misclassification.


RESULTS
Risks of adverse outcomes did not substantially vary within the range of z scores equivalent to 40-week weight gains of -4.3 to 9 kg for grade 1 obese, -8.2 to 5.6 kg for grade 2 obese, and -12 to -2.3 kg for grade 3 obese women. As gestational weight gain increased beyond these z score ranges, there were slight declines in risk of small-for-gestational age birth but rapid rises in cesarean delivery and large-for-gestational age birth. Risks of preterm birth and neonatal intensive care unit admission were weakly associated with weight gain. The bias analysis supported the validity of the conventional analysis.


CONCLUSIONS
Gestational weight gain below national recommendations for obese mothers (5-9 kg) may not be adversely associated with fetal growth, gestational age at delivery, or mode of delivery.
From the aDepartment of Epidemiology, Graduate School of Public Health, bDepartment of Obstetrics, Gynecology, and Reproductive Sciences, School of Medicine, University of Pittsburgh, Pittsburgh, PA; cMagee-Womens Research Institute, Pittsburgh, PA; dDepartment of Epidemiology, Rollins School of Public Health, Emory University, Atlanta, GA; eDepartment of Obstetrics and Gynaecology, University of British Columbia, Vancouver, British Columbia, Canada; and fDivision of Epidemiology, University of California at Berkeley School of Public Health, Berkeley, CA.
Lisa M
LM
Bodnar
Sarah J
SJ
Pugh
Timothy L
TL
Lash
Jennifer A
JA
Hutcheon
Katherine P
KP
Himes
Sara M
SM
Parisi
Barbara
B
Abrams
Obesity (Silver Spring). 2014 Sep;22(9):1989-96
25164259
Epidemiology. 2007 Jan;18(1):67-72
17149141
Am J Obstet Gynecol. 2013 Sep;209(3):214.e1-11
23635421
Radiology. 1991 Oct;181(1):129-33
1887021
BJOG. 2011 Jan;118(1):55-61
21054761
Am J Clin Nutr. 2010 Jun;91(6):1642-8
20357043
BJOG. 2012 Nov;119(12):1503-11
22900903
Pediatr Res. 2011 Feb;69(2):175-80
21076366
Matern Child Health J. 2014 May;18(4):1038-47
24077985
MMWR Surveill Summ. 2014 Apr 25;63(3):1-62
24759729
BMC Pregnancy Childbirth. 2013 Dec 11;13:231
24330402
J Natl Cancer Inst. 1988 Oct 5;80(15):1198-202
3047407
Pediatrics. 2004 Nov;114(5):1341-7
15520119
Obstet Gynecol. 2011 Sep;118(3):569-575
21860285
Matern Child Health J. 2011 Apr;15(3):289-301
20306221
Obstet Gynecol. 2014 Apr;123(4):737-44
24785599
Birth. 2013 Jun;40(2):107-14
24635465
Obesity (Silver Spring). 2015 Mar;23(3):532-5
25707378
Obstet Med. 2012 Jun;5(2):58-64
27579137
Obes Rev. 2007 Jul;8(4):307-26
17578381
Obstet Gynecol. 2010 Jan;115(1):152-155
20027048
Paediatr Perinat Epidemiol. 2014 May;28(3):203-12
24673550
Obstet Gynecol. 2015 Jan;125(1):133-143
25560115
Paediatr Perinat Epidemiol. 2012 Mar;26(2):109-16
22324496
J Community Health. 2013 Apr;38(2):261-7
22961295
BMC Pregnancy Childbirth. 2011 Nov 21;11:96
22103736
BMC Med Res Methodol. 2008 Oct 30;8:70
18973665
Women Birth. 2015 Sep;28(3):e70-9
25866207
World Health Organ Tech Rep Ser. 2000;894:i-xii, 1-253
11234459
Clin Obstet Gynecol. 1997 Dec;40(4):704-14
9429784
Am J Prev Med. 2012 Jun;42(6):563-70
22608371
Am J Clin Nutr. 2010 Sep;92(3):644-51
20631201
Epidemiology. 2014 Jul;25(4):576-82
24815306