Review Article

Hemoglobin Concentration and Pregnancy Outcomes: A Systematic Review and Meta-Analysis

Table 1

Characteristics of included studies.

Authors, year (Reference number)Study designSample sizeMean ageCountry TrimesterPregnancy outcomesConfounding factors

Abeysena et al., 2010 [17]Prospective cohort817 Sri LankaFirstPTB, LBW, and SGANot specify

Kumar et al., 2010 [34]Prospective cohort2,027 IndiaFirst LBWMaternal age, parity, maternal height, maternal weight, BMI, and gestational age

Kidanto et al., 2009 [32]Case control1,72124aTanzaniaFirst PTB, LBW, and SBNot specify

Zhang et al., 2009 [16]Prospective cohort160,700NAChinaFirst
Second
Third
PTBMaternal age at delivery, education, occupation, parity, folic acid, BMI, time of first prenatal visit, and fetal gender

Zhang et al., 2009 [33]Prospective cohort164,667NAChinaFirst
Second
Third
SB, NDMaternal age at delivery, education, occupation, parity, folic acid, BMI, time of first prenatal visit, and fetal gender

Ren et al., 2007 [12]Retrospective cohort88,149 ChinaFirst PTB, LBW, and SGAMaternal age, gravidity, education, and BMI

Lee et al., 2006 [29]Prospective cohort248 KoreaThird PTB, LBWNot specify

Mamun et al., 2006 [30]Retrospective cohort1,584 BangladeshSecond SB, PDNot specify

Monawar Hosain et al., 2006 [31]Prospective cohort350NABangladeshFirstLBWNot specify

Levy et al., 2005 [11]Retrospective cohort153,396 IraelFirst PTB, LBW, and PDEthnicity, maternal age, placental problems, caesarean delivery, and nonvertex presentation

Little et al., 2005 [15]Retrospective cohort222,614NAEnglandFirst STB, NDPrematurity, birth weight

Ronnenberg et al., 2004 [10]Prospective cohort405 ChinaFirst PTB, LBWMaternal age, height, BMI, education, exposure to dust, noise, passive smoking, work stress, infant gender, and gestational age

Chang et al., 2003 [26]Retrospective cohort918 USASecond
Third
PTB, LBWParity, BMI, smoking, preeclampsia, and antenatal care

Hämäläinen et al., 2003 [27]Case control22,799 FinlandFirst
Second
Third
PTB, LBW, SGA, and PDNot specify

Xiong et al., 2003 [28]Retrospective cohort16,936 ChinaFirst PTB, LBW, and PDHospital stay, maternal age, maternal education, parity, gestational age at the first prenatal visit, BMI, hypertensive disorder in pregnancy, vaginal bleeding, and prior spontaneous abortion

Martí et al., 2001 [25]Case control543 VenezuelaThird PTBPlacenta abruption, PROM, previous premature labor, ANC visit, and antenatal bleeding

Zhou et al., 1998 [9]Prospective cohort829 ChinaFirst PTB, LBW, and SGANot specify

Onadeko et al., 1996 [24]Prospective cohort4,649NANigeriaThird LBW, SBNot specify

Rasmussen and Oian, 1993 [18]Retrospective cohort3,074NANorwayFirst
Second
PTB, SGANot specify

Knottnerus et al., 1990 [7]Prospective cohort79627aNetherlandThird PTB, LBWPregnancy induced hypertension

Median. LBW: low birth weight; NA: not available; ND: neonatal deaths; PD: perinatal deaths; PTB: preterm birth; SGA: small for gestational age; SB: still births.