Outcome pregnancy:
A total of 980 pregnant women were identified in the 49 clusters. Nine hundred and fifty-two (952) pregnant women were included in the final analysis (Figure 1). This study included a total of 44 stillbirth (SBR = 46.2 per 1000 births, 95% CI: 32.7–59.3) and the remaining nine hundred eight (908) mothers with live single birth completed the 7 days follow-up (Table 1).
Table 1 Outcome of pregnancy in a cohort of 952 births, Sana’a City, Yemen, 8/2015–12/2016.
Pregnancy outcomes
|
Total number
|
Mortality rate
|
(95% confidence interval)
|
Total singletons births 952
|
952
|
|
|
Total live singletons birth
|
908
|
|
|
Still births
|
44/908
|
46.2 per 1000 birth
|
(32.7–59.3)
|
Characteristics of mothers
More than three quarters (85.3%) of the births in the sample were women aged 18–34. The mean age of women at recruitment was 26.0 years (SD 5.7). Stillbirths were more likely to be born to mothers aged less than 18 year and 35 years and older. Only 3.3% of the births were to women less than 18 years. The proportion of mothers aged less than 18 years at first marriage was 36.1% while 27.8% was mothers aged less than 18 years at first pregnancy. Most mothers came from slum areas (59.3%), and the proportion of illiteracy was 18.3%. Only 26.3% of the women were nulliparous. Around 9% of multiparous mothers had previously experienced a stillbirth. A total of 642 women (72%) went for antenatal care (ANC) prior to birth. ANC attendance differed according to parity and 33.2% of nulliparous mothers completed in excess of four ANC visits. This compared to 66.8% among multiparous mothers. Among births whose mothers received ANC, nearly half (48.2%) received the initial visit during the first trimester of pregnancy, whereas 31.6% waited until the third trimester of pregnancy to seek care. In spite of high attendance at antenatal clinics, 41.3% (393) of births were delivered at home where 21% (200) of births were assisted by untrained health personnel. Nine percent of women were cigarettes smokers, while 20.2% were water pipe tobacco smokers. Around half of the women (50.0%) were khat chewers, and 3% of the women had a history of female genital mutilation. Detail of other characteristics are shown in Table 2.
Table 2 distribution of factors analysed with experiencing stillbirth among 952 pregnant women in Sana’a City, Yemen, 8/2015–12/016.
Variables/factors
|
Total births (n = 952)
|
Stillbirths (n=44)
|
n
|
%
|
n
|
%
|
A.Socio-demographic factors
|
|
|
|
|
Maternal age at birth (years)
|
26.0± 5.70
|
|
28.0 ± 8.14
|
|
< 18
|
31/952
|
3.3
|
4/31
|
12.9
|
18 - 34
|
812/952
|
85.3
|
26/812
|
3.2
|
35 or more
|
109/952
|
11.4
|
14/109
|
12.8
|
Mother’s age at first marriage (years)
|
19.0± 3.75
|
|
19.0 ± 4.31
|
|
< 18
|
344/952
|
36.1
|
22/344
|
6.4
|
18 - 34
|
605952
|
63.6
|
22/605
|
3.6
|
35 or more
|
3/952
|
0.3
|
0
|
0.0
|
Mother’s age at first pregnancy (years)
|
20.0 ± 3.87
|
|
20.0 ± 4.71
|
|
< 18
|
265/952
|
27.8
|
17/265
|
6.4
|
18 - 34
|
681/952
|
71.5
|
26/681
|
3.8
|
35 or more
|
6/952
|
0.6
|
1/6
|
16.7
|
Place of residence (district)
|
|
|
|
|
Urban
|
387/952
|
40.7
|
18/387
|
5.7
|
Slum
|
565/952
|
59.3
|
26/565
|
4.6
|
Mother’s level of education
|
|
|
|
|
Illiteracy
|
174/952
|
18.3
|
9/174
|
5.2
|
Primary/Intermediate
|
382/952
|
40.1
|
15/382
|
3.9
|
Secondary
|
283/952
|
(29.7)
|
14/283
|
4.9
|
University and above
|
113/952
|
11.9
|
6/113
|
5.3
|
Mother's work
|
|
|
|
|
Yes
|
69/952
|
7.2
|
4/69
|
5.8
|
No
|
883/952
|
92.8
|
40/883
|
4.5
|
Monthly income a(YR)
|
|
|
|
|
Most poor (<35000)
|
243/952
|
25.5
|
7/243
|
2.9
|
Middle poor (35000-74000)
|
549/952
|
57.7
|
27/549
|
4.9
|
Least poor (=/> 75000)
|
160/952
|
16.8
|
10/160
|
6.3
|
Number of Family Member
|
|
|
|
|
2-4
|
372/952
|
39.1
|
12/272
|
3.2
|
5-7
|
297/952
|
31.2
|
16/297
|
5.4
|
8 or more
|
283/952
|
29.7
|
16/283
|
5.7
|
Table 2 distribution of factors analysed with experiencing stillbirth among 952 pregnant women in Sana’a City, Yemen, 8/2015–12/016 (Continued)
Family type
|
|
|
|
|
Multi-nuclear
|
427/952
|
44.9
|
24/427
|
5.6
|
Nuclear
|
525/952
|
55.1
|
20/525
|
3.8
|
B. Prenatal and past obstetric factors
|
|
|
|
|
Gravidity
|
|
|
|
|
Primigravida
|
222/952
|
23.3
|
16/222
|
7.2
|
Multigravida
|
730/952
|
76.7
|
28/730
|
3.8
|
Parity
|
|
|
|
|
Primipara 0
|
250/952
|
26.3
|
17/250
|
6.8
|
1
|
231/952
|
24.3
|
3/231
|
1.3
|
2 - 4
|
387/952
|
40.7
|
16/387
|
4.1
|
≥ 5
|
84/952
|
8.8
|
8/84
|
9.5
|
History of stillbirths
|
|
|
|
|
Yes
|
104/952
|
14.2
|
7/104
|
6.7
|
No
|
626/952
|
85.8
|
21/626
|
3.4
|
Female genital mutilation
|
|
|
|
|
Yes
|
24 (2.5)
|
|
3/24
|
12.5
|
No
|
928 (97.5)
|
|
41/928
|
4.4
|
Spacing (n=730, primigravidae excluded)1
|
|
|
|
< 24 months
|
317 /730
|
43.4
|
8/317
|
2.5
|
24 to 60 months
|
283/730
|
38.8
|
10/283
|
3.5
|
> 60 months
|
130/730
|
17.8
|
10/130
|
7.7
|
Number of antenatal visits
|
3.3 ± 0.71
|
|
3.6 ± 2.17
|
|
Not visit
|
32/952
|
3.4
|
0/32
|
0
|
≤4
|
682/952
|
71.6
|
34/682
|
5.0
|
≥5
|
238/ 952
|
25.0
|
10/238
|
4.2
|
Time of 1st ANC visit 2 (n=917)
|
|
|
|
|
First trimester
|
442/917
|
48.2
|
16/422
|
3.6
|
Second trimester
|
185/917
|
20.2
|
10/185
|
5.4
|
Third trimester
|
290/917
|
31.6
|
18/290
|
6.2
|
Table 2 distribution of factors analysed with experiencing stillbirth among 952 pregnant women in Sana’a City, Yemen, 8/2015–12/016 (Continued)
Maternal bTT vaccine (at least 1 dose)
|
|
|
|
|
Received
|
747/952
|
78.5
|
27/747
|
3.6
|
Not Received
|
205/952
|
21.5
|
17/205
|
8.3
|
Maternal Anaemia (g/dl) 3(n=951)
|
|
|
|
|
< 12.3 g/dl
|
282/951
|
29.7
|
19/282
|
6.7
|
≥ 12.3 g/dl
|
669/951
|
70.0
|
25/669
|
3.7
|
Maternal arm circumference4(MUAC, cm)
|
|
|
|
|
< 21 CMb
|
15/951
|
1.6
|
0
|
0.0
|
21 - 22.9 CM c
|
41/951
|
4.3
|
1/41
|
2.4
|
23 or more CMd
|
895/951
|
94.1
|
43/895
|
4.8
|
C. Special habits factors
|
|
|
|
|
Cigarette smoking
|
|
|
|
|
Smoker
|
81/952
|
8.5
|
4/81
|
4.9
|
Not smoker
|
871/952
|
91.5
|
40/871
|
4.6
|
Water pipe smoker (Shisha)
|
|
|
|
|
Yes
|
192/952
|
20.2
|
8/192
|
4.2
|
No
|
760/952
|
79.8
|
36/760
|
4.7
|
Orange snuff (smokeless tobacco) Smoker
|
|
|
|
|
Yes
|
16/952
|
1.7
|
3/16
|
18.8
|
No
|
936/952
|
98.3
|
41/936
|
4.4
|
Khat chewer during this pregnancy
|
|
|
|
|
Yes
|
476/952
|
50.0
|
25/476
|
5.3
|
No
|
476/952
|
50.0
|
19/476
|
4.0
|
D. Birth factors
|
|
|
|
|
Place of birth
|
|
|
|
|
Home birth
|
393/952
|
41.3
|
13/393
|
3.3
|
Health facility birth
|
559/952
|
58.7
|
31/559
|
5.5
|
Table 2 distribution of factors analysed with experiencing stillbirth among 952 pregnant women in Sana’a City, Yemen, 8/2015–12/016 (Continued)
Birth attendants
|
|
|
|
|
Trained personnel
|
752/952
|
79.0
|
35/752
|
4.7
|
Untrained personnel
|
200/952
|
21.0
|
9/200
|
4.5
|
Vaginal bleeding at third trimester
|
|
|
|
|
Yes
|
105/952
|
11.0
|
10/105
|
9.5
|
No
|
847/952
|
89.0
|
34/847
|
4.0
|
Prolonged Labour 5 (n=906)
|
|
|
|
|
Yes
|
327/906
|
36.1
|
22/327
|
6.7
|
No
|
579/906
|
63.9
|
16/579
|
2.8
|
Baby’s position 6(n=789)
|
|
|
|
|
Normal position
|
760/789
|
96.3
|
26/760
|
3.4
|
Malposition
|
29/789
|
3.7
|
7/29
|
24.1
|
E. Foetal factors
|
|
|
|
|
Birth weight (g) 7 (n=947)
|
|
|
|
|
Low birth weight (< 2500 g)
|
169/947
|
17.8
|
31/169
|
18.3
|
Normal birth weight (≥ 2500 g)
|
778/947
|
82.2
|
8/778
|
1.0
|
Sex of newborn
|
|
|
|
|
Male
|
517/952
|
54.3
|
30/517
|
5.8
|
Female
|
435/952
|
45.7
|
14/455
|
3.2
|
Gestation age (weeks)
|
|
|
|
|
Preterm (< 37 weeks)
|
101/952
|
10.6
|
20/101
|
19.8
|
Term (≥ 37 weeks)
|
851/952
|
89.4
|
24/851
|
2.8
|
1 Prmigravidae excluded (n=222), 2 There were 32 cases never on antenatal care visits,
3,4 One mother was not Hb tested and one mother did have MUAC recorded, 5 In 46 cases it was unknown whether there was prolonged labour, 6 160 births not counted (caesarean section) and 3 cases were unknown,
7 For 5 cases birth weight was not recorded.
a(YR)- Yemeni Riyal (1 USD$ = 250 YR), bTT-Tetanus Toxoid, b Severe acute malnutrition, cModerate acute malnutrition, dNormal
|
Distribution of stillbirths
There were a total of 44 stillbirths that occurred in 27 out of 49 clusters. The highest observed risk in a cluster was 166.7 per 1000 births within Al-Tahreer district was 66.7 per 1000 births (Table 3). Twelve clusters seem to have the highest stillbirth’s rate and represent 66 % of the total stillbirths. Seven clusters are slum areas and form around one third (32%) of the total stillbirths. There was no remarkable differences in proportion of stillbirths between urban (4.7%) and slum areas (4.6%).
Table 3 Outcome of pregnancy in a cohort of 952 births, Sana’a City, Yemen, 8/2015–12/2016.
No.
|
District
|
No. of clusters
|
Number of births/expected total birth (%)
|
SBR
N(/1000)
|
1
|
Al-Safyah
|
6
|
118/120 (93.3)
|
6/118 (50.8)
|
2
|
Al-Thawrah
|
10
|
194/200 (97.0)
|
7/194 (36.1)
|
3
|
Shu’ub
|
13
|
253/260 (97.3)
|
6/253 (23.7)
|
4
|
Al-Tahreer
|
4
|
75/80 (93.8)
|
5/75 (66.7)
|
5
|
Ma’ain
|
16
|
312/320 (97.5)
|
20/312 (64.1)
|
Total
|
|
49
|
952/980 (97.1)
|
44/952 (46.2 per 1000 births)
|
Socio-demographic factors (Table 4A)
There is a highly significant association between stillbirth and mother age at birth. With regards to age at birth, teenage mothers (aged < 18) and older women (aged 35 and above) were observed to have higher stillbirths (RR 4.03; 95% CI: 1.15–10.81) and (RR 4.01; 95% CI: 2.16–7.44), respectively. Residence slums areas of Sana’a City (p= 0.972), family type (p=0.188) did not appear to be associated with.
Table 4A Risk factors for stillbirths (SB) in bivariate analysis in a cohort of 952 births, Sana’a City, Yemen, 8/2015–12/2016.
Variable/Factor
|
aSB/total (%)
|
Stillbirth
rate per 1000
|
Unadjusted bRR
|
(95% CI)c
|
P-value
|
A. Socio-demographic
|
|
|
|
|
|
Maternal age at birth (Years) (n=952)
|
|
|
|
|
|
< 18
|
4/31 (12.9)
|
129.0
|
4.03
|
1.51-10.84
|
0.006
|
18 - 34
|
26/812 (3.2)
|
32.0
|
|
1.00
|
|
≥ 35
|
14/109 (12.8)
|
128.4
|
4.01
|
2.16-7.44
|
<0.001
|
Place of residence (district) (n=952)
|
|
|
|
|
|
Slum
|
26/565 (4.6)
|
46.0
|
0.99
|
0.55-1.78
|
0.972
|
Urban
|
18/387 (4.7)
|
46.5
|
|
1.00
|
|
Mother's education (n=952)
|
|
|
|
|
|
Illiteracy
|
9/174 (5.2)
|
51.7
|
0.97
|
0.36-2.66
|
0.959
|
Primary/Intermediate
|
15/382 (3.9)
|
39.3
|
0.74
|
0.29-1.86
|
0.522
|
Secondary
|
14/283 (4.9)
|
49.5
|
0.93
|
0.37-2.36
|
0.882
|
University and above
|
6/113 (5.3)
|
53.1
|
|
1.00
|
|
Mother's work (n=952)
|
|
|
|
|
|
Yes
|
4/69 (5.8)
|
58
|
1.28
|
0.47-3.47
|
0.628
|
No
|
40/883 (4.5)
|
45.3
|
|
1.00
|
|
No. of Family member (n=952)
|
|
|
|
|
|
2-4
|
12/272 (3.2)
|
32.3
|
|
1.00
|
|
5-7
|
16/297 (5.4)
|
53.9
|
1.67
|
0.80-3.48
|
0.170
|
≥ 8
|
16/283 (5.7)
|
56.5
|
1.75
|
0.84-3.65
|
0.133
|
Family type (n=952)
|
|
|
|
|
|
Multi-nuclear
|
24/427 (5.6)
|
56.2
|
1.48
|
0.83-2.63
|
0.188
|
Nuclear
|
20/525 (3.8)
|
38.1
|
|
1.00
|
|
aSB-Stillbirth, bRR- Relative risk, cCI- Confidence interval
|
Prenatal and past obstetric factors (Table 4B)
Mothers with Multigravida increased the risk of stillbirths (RR 1.88; 95% CI: 1.043.41) compared to primigravida. The result also indicates that mothers with higher parities (five and above) were 2.30 times more likely to experience a stillbirth (95% CI: 1.02–5.21).
Further, inter-pregnancy interval more than 60 months led to an increase in the risk of stillbirth by 3.05 times (95% CI: 1.23-7.55) whereas mothers who received tetanus toxoid vaccine had decreased risk of stillbirths by 56% relative to the mothers who had not received tetanus toxoid vaccine (RR 0.44; 95% CI:0.24-0.78). Furthermore, women with a low Hb (< 12.3 g/dl) had a significantly increased risk of stillbirth (RR 1.80; 95% CI: 1.01-3.21) in the univariate analysis compared to the women with normal haemoglobin. Female genital mutilation (RR 2.82; 95% CI: 0.94-8.47, p =0.065) did not appear to be significant factor for stillbirths.
Table 4B Risk factors for stillbirths (SB) in bivariate analysis in a cohort of 952 births, Sana’a City, Yemen, 8/2015–12/2016
Variable/Factor
|
aSB/total (%)
|
Stillbirth
rate per 1000
|
Unadjusted bRR
|
(95% CI)c
|
P-value
|
B. Prenatal and past obstetric
|
|
|
|
|
|
Gravidity (n=952)
|
|
|
|
|
|
Primigravida
|
16/222 (7.2)
|
72.1
|
1.88
|
1.04-3.41
|
0.038
|
Multigravida
|
28/730 (3.8)
|
38.4
|
|
1.00
|
|
Parity (n=952)
|
|
|
|
|
|
Primipara 0
|
17/250 (6.8)
|
68
|
1.64
|
0.84-3.19
|
0.142
|
1
|
3/231 (1.3)
|
13
|
0.31
|
0.09-1.07
|
0.063
|
2 - 4
|
16/387 (4.1)
|
41.3
|
|
1.00
|
|
≥ 5
|
8/84 (9.5)
|
95.2
|
2.30
|
1.02-5.21
|
0.045
|
Female genital mutilation (n=952)
|
|
|
|
|
|
Yes
|
3/24 (12.5)
|
125
|
2.82
|
0.94-8.47
|
0.065
|
No
|
41/928 (4.4)
|
44.2
|
|
1.00
|
|
Table 4B (Continued)
Inter-pregnancy interval1 (n=730)
|
|
|
|
|
|
< 24 months
|
8/302 (2.6)
|
26.5
|
|
1.00
|
|
24 to 60 months
|
10/298 (3.4)
|
33.6
|
1.27
|
0.51-3.17
|
0.613
|
> 60 months
|
10/130 (7.7)
|
76.9
|
2.90
|
1.17-7.19
|
0.021
|
Maternal cTT vaccine (n=952)
|
|
|
|
|
|
Received
|
27/747 (3.6)
|
36.1
|
0.44
|
0.24-0.78
|
0.006*
|
Not Received
|
17/205 (8.3)
|
82.9
|
|
1.00
|
|
Maternal anaemia (n=951) 2
|
|
|
|
|
|
Hb < 12.3 g/dl
|
19/282 (6.7)
|
67.4
|
1.80
|
1.01-3.21
|
0.046
|
Hb ≥ 12.3 g/dl
|
25/669 (3.7)
|
37.4
|
|
1.00
|
|
aSB-Stillbirth, bRR- Relative risk, cCI- Confidence interval, *Protective effect, cTT-Tetanus Toxoid, 1 Excludes primipara (222 cases), 2One mother was not Hb tested.
|
Special habits factors (Table 4C)
The unadjusted analysis showed that mothers who used orange snuff (smokeless tobacco) had a significantly increased risk of stillbirth (RR 4.28; 95% CI: 1.48-12.39), whereas Khat chewers RR 1.32; 95% CI: 0.73-2.36, p =0.356) did not appear to be significant factor for stillbirths.
Table 4C Risk factors for stillbirths (SB) in bivariate analysis in a cohort of 952 births,
Sana’a City, Yemen, 8/2015–12/2016
Variable/Factor
|
aSB/total (%)
|
Stillbirth
rate per 1000
|
Unadjusted bRR
|
(95% CI)c
|
P-value
|
C. Special habits
|
|
|
|
|
|
Orange snuff (smokeless tobacco) smoker (n=952)
|
|
|
|
|
|
Yes
|
3/16 (18.8)
|
187.5
|
4.28
|
1.48-12.39
|
0.007
|
No
|
41/936 (4.4)
|
43.8
|
|
1.00
|
|
Khat chewer (n=952)
|
|
|
|
|
|
Yes
|
25/476 (5.3)
|
52.5
|
1.32
|
0.73-2.36
|
0.356
|
No
|
476 (4.0)
|
39.9
|
|
1.00
|
|
aSB-Stillbirth, bRR- Relative risk, cCI- Confidence interval
|
Birth factors (Table 4D)
The result indicates the three reasons for home birth where unavailability of birth services placed births at the greatest risk, at nearly nine times the risk of stillbirth as compared to births to women without this reason (RR 9.23; 95% CI: 1.69-50.44). This association was statistically significant.
One of the birth attendant categories showed significant protective effect of stillbirth. These was the birth attendant by the midwife (RR 0.21; 95% CI: 0.06-0.66).
Prolonged labour (> 24 hours) (RR 2.43, 95% CI: 1.30-4.57), Births to women experiencing longer duration of water breaks (≥ 24 hours) before births (RR 4.41, 95% CI: 2.23-8.74), Baby’s abnormal presentation (RR 8.18, 95% CI: 4.35-15.40) were statistically associated with stillbirths.
Table 4D Risk factors for stillbirths (SB) in bivariate analysis in a cohort of 952 births, Sana’a City, Yemen, 8/2015–12/2016
Variables/factors
|
aSB/total (%)
|
Stillbirth
rate per 1000
|
Unadjusted bRR
|
(95% CI)c
|
P-value
|
D. Birth factors
|
|
|
|
|
|
Place of birth (n=952)
|
|
|
|
|
|
Home birth
|
13/393 (3.3)
|
33.1
|
0.60
|
0.32-1.13
|
0.111
|
Health facility birth
|
31/559 (5.5)
|
55.5
|
|
1.00
|
|
Reason for home birth 1 (n=388)
|
|
|
|
|
|
Service not available
|
2/13 (15.4)
|
153.8
|
9.23
|
1.69-50.44)
|
0.010
|
Service too far
|
0/17 (0.0)
|
0.0
|
|
0
|
|
High cost
|
5/153 (3.3)
|
32.7
|
1.96
|
0.48-8.07
|
0.351
|
Premature/sudden birth
|
2/25 (8.0)
|
80
|
4.80
|
0.84-27.34
|
0.077
|
Home is better
|
2/180 (1.1)
|
11.1
|
|
1.00
|
|
Birth attendants (n=952)
|
|
|
|
|
|
Female/male doctor
|
31/500 (6.2)
|
62
|
|
1.00
|
|
Midwife
|
3/236 (1.3)
|
12.7
|
0.21
|
0.06-0.66
|
0.008*
|
Nurse
|
1/16 (6.3)
|
62.5
|
1.00
|
0.15-6.93
|
0.994
|
Traditional birth attendant (TBA)
|
4/95 (4.2)
|
42.1
|
0.68
|
0.25-1.88
|
0.456
|
Relatives
|
5/105 (4.8)
|
47.6
|
0.77
|
0.31-1.93
|
0.574
|
Table 4D (Continued)
Prolonged labour (n=906)2
|
|
|
|
|
|
Yes
|
22/327 (6.7)
|
67.3
|
2.43
|
1.30-4.57
|
0.006
|
No
|
16/579 (2.8)
|
27.6
|
|
1.00
|
|
Prolonged rupture of
membranes (≥ 2 hours) (n=754)3
|
|
|
|
|
|
Yes
|
13/106 (12.3)
|
122.6
|
4.41
|
2.23-8.74
|
<0.001
|
No
|
18/648 (2.8)
|
27.8
|
|
1.00
|
|
Baby’s position (n=789)4
|
|
|
|
|
|
Normal presentation
|
26/760 (3.4)
|
34.2
|
|
1.00
|
|
Abnormal presentation
|
9/29 (31.0)
|
310.0
|
8.18
|
4.35-15.40
|
<0.001
|
aSB-Stillbirth, bRR- Relative risk, cCI- Confidence interval, *Protective effect, 1 Only mothers who those at home birth, 2 For 46 of mothers the prolonged labour was unknown, 3 There were 198 cases of unknown prolonged rupture of membranes, 4 Excluding 160 cases with caesarean and 3 cases with unknown baby presentation.
|
Foetal factors (Table 4E)
The risk of stillbirth was 17.84 (95% CI: 8.35-38.11) times greater among 'low birth weight' births compared to the normal birth weight babies. In addition, babies with gestational age < 37 weeks at the time of birth experienced significantly higher stillbirths (RR 6.31; 95% CI: 3.61-11.05) as compared to term births.
Table 4E Risk factors for stillbirths (SB) in bivariate analysis in a cohort of 952 births, Sana’a City, Yemen, 8/2015–12/2016
Variables/factors
|
aSB/total (%)
|
Stillbirth
rate per 1000
|
Unadjusted bRR
|
(95% CI)c
|
P-
value
|
E. Foetal factors
|
|
|
|
|
|
Birth weight (g) (n=947)1
|
|
|
|
|
|
Low birth weight (< 2500 g)
|
31/169 (18.3)
|
183.4
|
17.84
|
8.35-38.11
|
<0.001
|
Normal birth weight (≥ 2500 g)
|
8/778 (1.0)
|
10.3
|
|
1.00
|
|
Sex of newborn
|
|
|
|
|
|
Male
|
30/517 (5.8)
|
58
|
1.80
|
0.97-3.36
|
0.063
|
Female
|
14/435 (3.2)
|
32.2
|
|
1.00
|
|
Foetal gestational age (weeks) (n=952)
|
|
|
|
|
|
Preterm (< 37 weeks)
|
20/100 (18.0)
|
180.2
|
6.31
|
3.61-11.05
|
<0.001
|
Term (≥ 37 weeks)
|
24/847 (2.9)
|
28.5
|
|
1.00
|
|
aSB-Stillbirth, bRR- Relative risk, cCI- Confidence interval,1 Excludes 5 cases was not obtained birth weight
|
Population attributable risk percentage (PAR%)
Table 5 shows population attributable risk percentage (PAR%) for stillbirths where among the stillbirth factors, the low birth weight (< 2500 g), Orange snuff smoker resulted in the greatest PAR (76.9 , 66.2 percent), respectively, followed by maternal anemia (Hb g/dl) (41.8 percent ) , and elimination their help to eliminate the proportion of stillbirths.
Table 5 Population attributable risk percentage for stillbirths
Variables /Factors
|
Ba
|
Unadjusted RRb
|
Adjusted RRb
|
Prevalence (%)
|
PAR%d
|
Mother's age at birth (years)
|
|
|
|
|
|
< 20 y vs. 20 y+
|
1.309
|
3.88
|
3.7
|
8.2
|
18.1
|
Maternal anemia (Hb g/dl)
|
|
|
|
|
|
< 12.3 g/dl vs. ≥ 12.3 g/dl
|
0.801
|
1.64
|
2.23
|
58.5
|
41.8
|
Orange snuff smoker
|
|
|
|
|
|
Yes vs. No
|
1.451
|
4.28
|
4.27
|
0.6
|
66.2
|
Newborn birth weight (g)
|
|
|
|
|
|
LBW vs. Normal birth weight
|
2.702
|
17.84
|
14.9
|
23.9
|
76.9
|
Ba - Coefficient for adjusted RR, RRb - Relative Risk, PARd - Population Attributable Risk percentage, LBW-Low birth weight
|
Multivariable analysis: predictors of stillbirths
In the multivariate analysis, the risk of perinatal death was adjusted for socio-demographics factors, prenatal and past obstetric factors, special habits factors, birth factors and foetal factors. Backward elimination of the variables one by one was done to obtain the final model (Table 6). In this model, the variables that are observed to significantly influence perinatal deaths are mother’s age at birth, maternal anaemia, prolonged labour, baby’s position, newborn birth weight and foetal gestational age.
Table 6 Risk factors for stillbirth in multivariable analysis in a cohort of 952 births, Sana’a City, Yemen, 8/2015–12/2016.
Variable /Factor
|
Unadjusted
RRb
|
Adjusted
RRb
|
( 95% CIc)
|
Adjusted P-value
|
Mother's age at birth(years)
|
|
|
|
|
< 20 vs. 20-34
|
3.88
|
3.70
|
1.76-7.76
|
<0.001
|
Maternal anaemia (Hb g/dl)
|
|
|
|
|
< 12.3 g/dl vs. ≥ 12.3 g/dl
|
1.64
|
2.23
|
1.67-2.98
|
< 0.001
|
Orange Snuff (smokeless tobacco)
|
|
|
|
|
Yes vs. No
|
4.28
|
4.27
|
1.17-15.55
|
0.028
|
Prolonged Labour (> 24 hours)
|
|
|
|
|
Yes vs. No
|
2.43
|
2.02
|
1.38-2.96
|
<0.001
|
Prolonged rupture of membranes
(≥ 24 hours)
|
|
|
|
|
≥ 24 hours vs. < 24 hours
|
4.42
|
2.22
|
1.66-2.98
|
<0.001
|
Baby’s position
|
|
|
|
|
Malposition vs. Normal position
|
9.07
|
4.60
|
2.97-7.12
|
<0.001
|
Newborn birth weight (g)
|
|
|
|
|
*LBW vs. Normal birth weight
|
17.84
|
14.90
|
4.30-51.75
|
<0.001
|
Foetal gestational age (weeks)
|
|
|
|
|
Preterm vs. Term
|
7.02
|
5.60
|
2.52-12.41
|
<0.001
|
RRb - Relative Risk , 95% CIc – Confidence interval, *LBW-low birth weight
Deviance= 0.1393951, Pearson = 1.789529 , BIC = -4107.343
|