Table 1
Study variable description.
| Variable | Original Data Format | Analysis Variable Format |
|---|---|---|
| Outcome Variable | ||
| Neonatal Mortality | Continuous – Age at death in days, months or years | If response was ≤28 days then neonatal mortality was categorized as “Yes” or 1, otherwise, neonatal mortality = “No” or 0. |
| Exposure Variable | ||
| *Maternal Body Mass Index (BMI) Categories | Continuous – BMI was calculated and recorded post survey from measured weight (W) and height (H) (BMI = W/H2) | <18.5 kg/m2 was categorized as underweight, 18.5–24.99 kg/m2 was categorized as optimum, 25–29.99 kg/m2 was categorized as overweight, ≥30 kg/m2 was categorized as obese. |
| Covariates | ||
| Maternal Age at Index Birth | Absent in the original dataset. | Dates in the dataset was stored as century month codes (CMC), which is the number of months since the start of the century). To obtain maternal age at the time of the index birth, the CMC of date of birth of the index child was subtracted from the CMC of date of birth of the respondent and divided by 12 to give the maternal age at the time of index birth. |
| Maternal Education Level |
|
|
| Area of Residence |
|
|
| Access to Prenatal Care | The type of person who gave prenatal care to the respondent prior to birth was recorded as:
| Access to prenatal care was defined as care provided by skilled health care personnel [13]. These are typically Doctors, Nurses and Midwives [14]. Hence, access to prenatal care was categorized as “Yes” or 1 if care was provided by a Doctor, Nurse or Midwife, otherwise “No” or 0. |
| Birth Order | Discrete – birth order number of the child which gives the order in which the child was born | Same as original data format |
| Multiple Births |
|
|
| Region | Absent in the dataset | This variable was created by categorizing the country of the respondent into regional classification following the method of the UN Statistics Division [15]
|
| Time Interval since Index Birth (years) | Absent in the dataset | The CMC of the date of interview was subtracted from the CMC of the date of birth of child to provide the time interval since the index birth. |
Figure 1
Flow diagram of sample selection.
Table 2
Frequencies and percentages of missing values per variable.
| Variable | Frequency of missing values (n) | Percent of missing values (%) |
|---|---|---|
| Neonatal mortality | 64,878 | 36.9 |
| Body mass index | 64,878 | 36.9 |
| Mothers age at Index Birth | 0 | 0.0 |
| Mother’s education | 20 | 0.0 |
| Place of residence | 0 | 0.0 |
| Access to prenatal care | 0 | 0.0 |
| Birth order | 0 | 0.0 |
| Twin/multiple birth | 0 | 0.0 |
| Region of residence | 0 | 0.0 |
Table 3
Individual characteristics of women reporting neonatal mortality in 34 SSA countries under complete case analysis.
| Characteristics | No (n = 109,140) Number (%) | Yes (n = 1,842) Number (%) | All women (n = 110,982) Number (%) | P-value |
|---|---|---|---|---|
| Maternal BMI Category | ||||
| Optimum | 71,356 [65.4] | 1,144 [62.1] | 72,501 [65.3] | 0.000 |
| Underweight | 10,671 [9.8] | 164 [8.9] | 10,835 [9.8] | |
| Overweight | 18,863 [17.3] | 332 [18.0] | 19,195 [17.3] | |
| Obese | 8,250 [7.6] | 204 [11.0] | 8,451 [7.6] | |
| Maternal Age at Index Birth (years) | ||||
| Mean (SD*) | 29.6 [6.3] | 31.5 [6.9] | 29.6 [6.3] | |
| Maternal Education Level | ||||
| No Education | 43,452 [39.8] | 791 [43.0] | 44,244 [39.9] | 0.002 |
| Primary | 36,592 [33.5] | 629 [34.1] | 37,220 [33.5] | |
| Secondary or Higher | 29,082 [26.7] | 422 [22.9] | 29,504 [26.6] | |
| Area of Residence | ||||
| Urban | 36,350 [33.3] | 615 [33.4] | 36,964 [33.3] | 0.315 |
| Rural | 72,790 [66.7] | 1,227 [66.6] | 74,018 [66.7] | |
| Prenatal Care | ||||
| Yes | 76,706 [70.9] | 1,172 [63.7] | 77,879 [70.2] | 0.000 |
| No | 32,434 [29.7] | 670 [36.4] | 33,103 [29.8] | |
| Birth Order | ||||
| Mean (SD) | 4.2 [2.4] | 5.0 [3.0] | 4.2 [2.5] | |
| Twin/Multiple Birth | ||||
| No | 106,855 [97.9] | 1,592 [86.4] | 108,447 [97.7] | 0.000 |
| Yes | 2,285 [2.1] | 250 [13.6] | 2,535 [2.3] | |
| Region | ||||
| East Africa | 45,187 [41.4] | 721 [39.2] | 49,508 [41.4] | 0.000 |
| West Africa | 44,310 [40.6] | 826 [44.8] | 45,135 [40.7] | |
| Middle Africa | 15,717 [14.4] | 236 [12.8] | 15,953 [14.4] | |
| Southern Africa | 3,926 [3.6] | 59 [3.2] | 3,985 [3.6] | |
| Time Interval since Index Birth (years) | ||||
| Mean (SD) | 2.0 [1.4] | 2.0 [1.5] | 2.0 [1.4] | |
| Total | 109,140 (98.3) | 1,842 (1.7) | 110,982 (100.0) |
[i] * SD = Standard Deviation.
Table 4
Overall and subgroup estimates of neonatal mortality and their standard errors under (a) complete case analysis and (b) multiple imputation in sub-Saharan Africa.
| Variable | (a) Complete case analysis | (b) Multiple imputations | ||||
|---|---|---|---|---|---|---|
| Estimate | S.E. | 95% CI | Estimate | S.E. | 95% CI | |
| Overall | 0.017 | 0.0004 | [0.016, 0.017] | 0.017 | 0.0003 | [0.016, 0.017] |
| Maternal BMI Category | ||||||
| Optimum | 0.016 | 0.0005 | [0.015, 0.017] | 0.017 | 0.0001 | [0.017, 0.018] |
| Underweight | 0.015 | 0.0011 | [0.013, 0.017] | 0.014 | 0.0003 | [0.014, 0.015] |
| Overweight | 0.017 | 0.0009 | [0.016, 0.019] | 0.021 | 0.0003 | [0.020, 0.021] |
| Obese | 0.024 | 0.0017 | [0.020, 0.027] | 0.023 | 0.0004 | [0.022, 0.024] |
| Maternal Education | ||||||
| No Education | 0.018 | 0.0006 | [0.017, 0.019] | 0.018 | 0.0005 | [0.017, 0.019] |
| Primary | 0.017 | 0.0007 | [0.015, 0.018] | 0.016 | 0.0005 | [0.015, 0.017] |
| Secondary or Higher | 0.014 | 0.0007 | [0.013, 0.016] | 0.015 | 0.0006 | [0.014, 0.016] |
| Area of Residence | ||||||
| Urban | 0.017 | 0.0007 | [0.016, 0.018] | 0.018 | 0.0006 | [0.017, 0.019] |
| Rural | 0.016 | 0.0005 | [0.015, 0.017] | 0.016 | 0.0004 | [0.015, 0.017] |
| Prenatal Care | ||||||
| No | 0.020 | 0.0008 | [0.018, 0.021] | 0.019 | 0.0006 | [0.018, 0.020] |
| Yes | 0.015 | 0.0004 | [0.014, 0.016] | 0.015 | 0.0004 | [0.015, 0.016] |
| Multiple Birth | ||||||
| No | 0.015 | 0.0004 | [0.014, 0.015] | 0.015 | 0.0003 | [0.014, 0.015] |
| Yes | 0.097 | 0.0059 | [0.085, 0.108] | 0.096 | 0.0047 | [0.087, 0.105] |
| Region | ||||||
| East Africa | 0.015 | 0.0006 | [0.014, 0.016] | 0.015 | 0.0005 | [0.014, 0.016] |
| West Africa | 0.019 | 0.0006 | [0.018, 0.020] | 0.019 | 0.0005 | [0.017, 0.019] |
| Middle Africa | 0.014 | 0.0009 | [0.012, 0.016] | 0.016 | 0.0008 | [0.015, 0.018] |
| Southern Africa | 0.016 | 0.0020 | [0.012, 0.020] | 0.016 | 0.0015 | [0.013, 0.019] |
| Number of observations | 110,982 | 175,860 | ||||
Table 5
Adjusted odds ratios for the multilevel logistic regression models under (a) complete case analysis and (b) multiple imputations in sub-Saharan Africa.
| Variable | (a) Complete case analysis | (b) Multiple imputations | ||
|---|---|---|---|---|
| Crude Odds Ratio (95% CI) | Adjusted Odds Ratio (95% CI) | Crude Odds Ratio (95% CI) | Adjusted Odds Ratio (95% CI) | |
| Maternal BMI Category | ||||
| Optimum | 1.00 | 1.00 | 1.00 | 1.00 |
| Underweight | 0.94 [0.79, 1.10] | 0.95 [0.81, 1.13] | 0.88 [0.76, 1.04] | 0.90 [0.77, 1.06] |
| Overweight | 1.12 [0.99, 1.27] | 1.09 [0.96, 1.24] | 1.15 [1.02, 1.30] | 1.12 [0.99, 1.27] |
| Obese | 1.56 [1.33, 1.82] | 1.47 [1.25, 1.73] | 1.48 [1.28, 1.70] | 1.40 [1.21, 1.63] |
| Mothers Age at Index Birth (years) | 1.05 [1.04, 1.05] | 1.03 [1.02, 1.04] | 1.04 [1.04, 1.05] | 1.02 [1.01, 1.03] |
| Maternal Education Level | ||||
| No Education | 1.00 | 1.00 | 1.00 | 1.00 |
| Primary | 1.04 [0.92, 1.17] | 1.15 [1.01, 1.30] | 1.01 [0.92, 1.11] | 1.09 [0.99, 1.21] |
| Secondary or Higher | 0.85 [0.74, 0.97] | 1.04 [0.89, 1.21] | 0.86 [0.77, 0.95] | 1.00 [0.89, 1.13] |
| Area of Residence | ||||
| Urban | 1.00 | 1.00 | 1.00 | |
| Rural | 0.95 [0.86, 1.05] | 0.85 [0.76, 0.95] | 0.92 [0.85, 0.99] | 0.82 [0.75, 0.90] |
| Prenatal Care | ||||
| No | 1.00 | 1.00 | 1.00 | 1.00 |
| Yes | 0.78 [0.70, 0.87] | 0.76 [0.68, 0.85] | 0.79 [0.72, 0.86] | 0.76 [0.70, 0.83] |
| Birth Order | 1.13 [1.12, 1.15] | 1.07 [1.04, 1.10] | 1.13 [1.11, 1.14] | 1.07 [1.04, 1.09] |
| Multiple Birth | ||||
| No | 1.00 | 1.00 | 1.00 | 1.00 |
| Yes | 7.27 [6.31, 8.39] | 6.67 [5.76, 7.72] | 7.13 [6.35, 7.99] | 6.56 [5.83, 7.38] |
| Region | ||||
| East Africa | 1.00 | 1.00 | 1.00 | 1.00 |
| West Africa | 1.18 [0.95, 1.47] | 1.13 [0.90, 1.42] | 1.17 [0.96, 1.44] | 1.11 [0.90, 1.37] |
| Middle Africa | 0.88 [0.66, 1.17] | 0.79 [0.59, 1.06] | 1.03 [0.79, 1.34] | 0.94 [0.72, 1.22] |
| Southern Africa | 1.04 [0.70, 1.55] | 1.11 [0.74, 1.66] | 1.10 [0.76, 1.57] | 1.17 [0.81, 1.69] |
| Time Interval since Index birth (years) | 1.00 [0.97, 1.03] | 0.95 [0.92, 0.98] | 1.01 [0.98, 1.03] | 0.96 [0.93, 0.98] |
| Number of observations | 110,982 | 175,840 | ||
Table 6
Timing of neonatal mortality under (a) complete case analysis and (b) multiple imputations in sub-Saharan Africa.
| Characteristics | Number of deaths | Complete case analysis | Multiple imputations | ||
|---|---|---|---|---|---|
| Crude O.R. [95% Cl] | Adjusted O.R. [95% Cl] | Crude O.R. [95% Cl] | Adjusted O.R. [95% Cl] | ||
| Days 0–1 | |||||
| Optimum (Ref) | 614 | 1.00 | 1.00 | 1.00 | 1.00 |
| Underweight | 84 | 0.83 [0.66, 1.05] | 0.86 [0.68, 1.08] | 0.85 [0.69, 1.04] | 0.89 [0.73, 1.09] |
| Overweight | 187 | 1.16 [0.99, 1.37] | 1.13 [0.96, 1.34] | 1.14 [0.96, 1.36] | 1.08 [0.90, 1.28] |
| Obese | 122 | 1.68 [1.38, 2.05] | 1.60 [1.30, 1.97] | 1.54 [1.28, 1.85] | 1.39 [1.15, 1.69] |
| Days 2–6 | |||||
| Optimum (Ref) | 294 | 1.00 | 1.00 | 1.00 | 1.00 |
| Underweight | 46 | 1.00 [0.73, 1.37] | 1.02 [0.75, 1.40] | 0.96 [0.72, 1.27] | 0.97 [0.79, 1.49] |
| Overweight | 85 | 1.08 [0.84, 1.37] | 1.04 [0.81, 1.33] | 1.10 [0.88, 1.39] | 1.02 [0.76, 1.36] |
| Obese | 62 | 1.59 [1.19, 2.14] | 1.48 [1.09, 2.02] | 1.43 [1.09, 1.86] | 1.35 [1.02, 1.79] |
| Days 7–27 | |||||
| Optimum (Ref) | 227 | 1.00 | 1.00 | 1.00 | 1.00 |
| Underweight | 34 | 1.18 [0.84, 1.65] | 1.19 [0.85, 1.67] | 1.06 [0.77, 1.45] | 1.08 [0.79, 1.49] |
| Overweight | 58 | 0.99 [0.74, 1.33] | 1.01 [0.75, 1.36] | 1.03 [0.78, 1.37] | 1.02 [0.76, 1.36] |
| Obese | 17 | 0.92 [0.60, 1.41] | 0.95 [0.61, 1.49] | 1.04 [0.70, 1.54] | 1.01 [0.67, 1.53] |
[i] Note: Ref – Reference category.
Figure 2
Forest plot of country-level association of maternal obesity and neonatal mortality under imputations.
Figure 3
Forest plot of country-level association of maternal obesity and neonatal mortality under complete case analysis.