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Table 4 Maternal, delivery and infant characteristics as risk factors for preterm birth and low birth weight—overall and site specific risk ratios with 95% confidence intervals and p values

From: Rates and risk factors for preterm birth and low birthweight in the global network sites in six low- and low middle-income countries

Characteristic

Relative risk (95% CI), p-value

Overall, all sites

DRC

Zambia

Kenya

Guatemala

Belagavi

Nagpur

Pakistan

Maternal age (20–35)

1.0

1.0

1.0

1.0

1.0

1.0

1.0

1.0

 < 20

1.41 (1.32, 1.49), < .0001

1.94 (1.61, 2.33), < .0001

1.68 (1.48, 1.90), < .0001

2.38 (2.08, 2.72), < .0001

1.32 (1.22, 1.42), < .0001

1.16 (1.06, 1.28), 0.0024

1.35 (1.11, 1.65), 0.0026

1.30 (1.15, 1.48), < .0001

 > 35

1.08 (1.00, 1.17), 0.0385

1.23 (1.02, 1.48), 0.0305

1.10 (0.89, 1.35), 0.3785

0.46 (0.19, 1.07), 0.0724

1.19 (1.05, 1.35), 0.0057

2.18 (1.48, 3.22), < .0001

1.35 (0.87, 2.10), 0.1758

0.91 (0.78, 1.07), 0.2510

Maternal education (University +)

1.0

1.0

1.0

1.0

1.0

1.0

1.0

1.0

 No formal education

1.28 (1.18, 1.38), < .0001

 

0.67 (0.54, 0.83), 0.0002

0.95 (0.49, 1.82), 0.8741

1.08 (0.89, 1.30), 0.4399

1.26 (1.10, 1.45), 0.0008

1.32 (1.06, 1.65), 0.0140

1.25 (1.04, 1.50), 0.0165

 Primary/secondary

1.13 (1.06, 1.21), 0.0002

 

0.78 (0.64, 0.96), 0.0201

0.93 (0.64, 1.35), 0.6876

1.11 (0.96, 1.27), 0.1620

0.98 (0.88, 1.08), 0.6455

1.39 (1.23, 1.57), < .0001

1.07 (0.87, 1.32), 0.5037

Parity (1–2)

1.0

1.0

1.0

1.0

1.0

1.0

1.0

1.0

 0

1.27 (1.21, 1.33), < .0001

1.95 (1.69, 2.25), < .0001

1.46 (1.36, 1.57), < .0001

2.14 (1.79, 2.57), < .0001

1.14 (1.03, 1.27), 0.0122

1.22 (1.08, 1.39), 0.0014

1.26 (1.16, 1.36), < .0001

1.12 (1.05, 1.20), 0.0010

 > 2

0.90 (0.86, 0.95), < .0001

0.92 (0.84, 1.01), 0.0822

0.90 (0.80, 1.03), 0.1159

0.69 (0.58, 0.82), < .0001

0.99 (0.87, 1.12), 0.8555

1.08 (0.99, 1.18), 0.0977

1.43 (1.03, 1.99), 0.0349

0.85 (0.79, 0.91), < .0001

Consumption of vitamins/calcium/iron

1.0

1.0

1.0

1.0

1.0

1.0

1.0

1.0

 Not consumed

1.30 (1.15, 1.47), < .0001

1.82 (1.44, 2.31), < .0001

2.94 (0.89, 9.77), 0.0783

1.90 (0.91, 3.95), 0.0875

1.22 (1.03, 1.45), 0.0227

2.17 (1.91, 2.46), < .0001

0.72 (0.29, 1.75), 0.4654

1.08 (1.01, 1.16), 0.0357

Received tetanus toxoid immunization

1.0

1.0

1.0

1.0

1.0

1.0

1.0

1.0

 Did not receive

1.13 (1.04, 1.23), 0.0030

1.39 (1.03, 1.86), 0.0294

0.67 (0.43, 1.05), 0.0806

0.75 (0.48, 1.16), 0.1939

0.92 (0.84, 1.01), 0.0664

0.57 (0.09, 3.54), 0.5503

1.15 (0.56, 2.39), 0.7008

1.23 (1.14, 1.33), < .0001

Number of ANC visits (4 +)

1.0

1.0

1.0

1.0

1.0

1.0

1.0

1.0

 0

1.88 (1.56, 2.27), < .0001

5.27 (3.76, 7.39), < .0001

15.00 (6.23, 36.10), < .0001

5.93 (4.06, 8.68), < .0001

1.29 (1.03, 1.60), 0.0257

3.14 (1.15, 8.54), 0.0252

0.35 (0.14, 0.87), 0.0234

1.32 (1.12, 1.55), 0.0007

 1–3

1.68 (1.55, 1.83), < .0001

3.17 (2.57, 3.91), < .0001

3.00 (2.22, 4.06), < .0001

2.62 (2.09, 3.29), < .0001

1.59 (1.47, 1.72), < .0001

2.13 (1.87, 2.44), < .0001

1.40 (1.12, 1.75), 0.0030

1.16 (1.09, 1.24), < .0001

No obstructive labor

1.0

1.0

1.0

1.0

1.0

1.0

1.0

1.0

 Had obstructive labor

0.78 (0.70, 0.87), < .0001

1.51 (1.20, 1.89), 0.0004

1.28 (0.84, 1.97), 0.2551

1.71 (1.19, 2.44), 0.0036

0.59 (0.43, 0.82), 0.0018

0.76 (0.59, 0.97), 0.0251

0.68 (0.56, 0.84), 0.0002

0.79 (0.71, 0.88), < .0001

No severe antepartum hemorrhage

1.0

1.0

1.0

1.0

1.0

1.0

1.0

1.0

 Had severe antepartum hemorrhage

5.18 (4.44, 6.04), < .0001

6.63 (5.04, 8.72), < .0001

10.24 (7.15, 14.66) < .0001

10.28 (6.29, 16.77), < .0001

8.52 (6.99, 10.40), < .0001

7.40 (6.22, 8.81), < .0001

8.00 (6.16, 10.38), < .0001

2.75 (2.44, 3.11), < .0001

No severe postpartum hemorrhage

1.0

1.0

1.0

1.0

1.0

1.0

1.0

1.0

 Had severe postpartum hemorrhage

1.22 (1.07, 1.40), 0.0035

1.10 (0.68, 1.77), 0.6996

1.67 (1.16, 2.42), 0.0062

3.42 (2.14, 5.46), < .0001

1.80 (1.31, 2.49), 0.0003

1.18 (0.97, 1.43), 0.0980

1.70 (0.90,3.20), 0.0996

0.96 (0.85,1.09), 0.5243

No hypertensive disorders

1.0

1.0

1.0

1.0

1.0

1.0

1.0

1.0

 Had hypertensive disorders

2.74 (2.48, 3.02), < .0001

2.64 (1.17, 5.96), 0.0193

4.54 (2.82, 7.31), < .0001

10.72 (5.60, 20.51), < .0001

2.84 (2.52, 3.19), < .0001

3.09 (2.77, 3.44), < .0001

3.18 (2.80, 3.61), < .0001

1.46 (1.25, 1.72), < .0001

No fetal malpresentation

1.0

1.0

1.0

1.0

1.0

1.0

1.0

1.0

 Had fetal malpresentation

1.74 (1.56, 1.93), < .0001

2.93 (1.68, 5.13), 0.0002

2.62 (1.58, 4.35), 0.0002

3.50 (1.90, 6.47), < .0001

1.80 (1.48, 2.19), < .0001

1.83 (1.42, 2.35), < .0001

1.17 (0.92, 1.50), 0.1985

1.57 (1.38, 1.78), < .0001

BMI, kg/m2 (18.5–24.9)

1.0

1.0

1.0

 

1.0

1.0

1.0

1.0

 < 18.5

1.33 (1.27, 1.39), < .0001

1.40 (1.28, 1.53), < .0001

1.39 (1.20, 1.62), < .0001

â–¡

1.42 (1.07, 1.88), 0.0139

1.26 (1.16, 1.38), < .0001

1.28 (1.15, 1.42), < .0001

1.40 (1.31, 1.50), < .0001

 ≥ 25.0

0.77 (0.72, 0.81), <.0001

0.68 (0.57, 0.80), < .0001

0.61 (0.54, 0.68), < .0001

â–¡

0.73 (0.66, 0.81), < .0001

1.12 (0.95, 1.33), 0.1603

0.82 (0.63, 1.07), 0.1503

0.76 (0.69, 0.84), < .0001

Hemoglobin (≥ 11 g/dL)

1.0

    

1.0

1.0

 

 10.0–10.9 g/dL (mild)

0.96 (0.87, 1.05), 0.3580

â–‘

â–‘

â–‘

â–‘

0.93 (0.82, 1.05), 0.2182

1.04 (0.89, 1.23), 0.6142

â–‘

 < 10.0 g/dL (moderate/severe)

1.12 (1.02, 1.23), 0.0137

â–‘

â–‘

â–‘

â–‘

1.08 (0.97, 1.21), 0.1754

1.25 (1.07, 1.46), 0.0046

â–‘

Sex of the baby (MALE)

1.0

1.0

1.0

1.0

1.0

1.0

1.0

1.0

 Female

1.01 (0.98, 1.04), 0.5527

1.18 (1.09, 1.28), < .0001

1.13 (1.08, 1.19), < .0001

1.00 (0.88, 1.13), 0.9487

0.94 (0.88, 0.99), 0.0236

0.86 (0.81, 0.92), < .0001

1.00 (0.94, 1.07), 0.9333

1.07 (1.01, 1.15), 0.0338

  1. □—BMI not calculated for Kenya because maternal height was not recorded before 2017
  2. ░—maternal hemoglobin not consistently collected at all GN sites except Belagavi, India and Nagpur, India
  3. Generalized linear models were used to evaluate the relationship of potential factors and the combination of prematurity and LBW and to develop point and interval estimates of relative risk associated with these factors. Generalized estimating equations were used to account for the correlation of outcomes within cluster to develop appropriate confidence intervals. The reference group is indicated by 1.0 in the Risk Ratio column
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Reproductive Health

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