Table 1.
Demographics of the study population at time of enrolment
| Overall (N=6514) | Participants with GBS colonisation (N=1572) | Participants without GBS colonisation (N=4942) | p value∗ | |
|---|---|---|---|---|
| Median age (IQR), years | 25 (22–30); n=6512 | 26 (22–30); n=1572 | 25 (21–29); n=4940 | 0·0015 |
| Age group, years | ·· | ·· | ·· | 0·010 |
| <20 | 1238/6512 (19·0%) | 269/1572 (17·1%) | 969/4940 (19·6%) | ·· |
| 20–<25 | 2148/6512 (33·0%) | 506/1572 (32·2%) | 1642/4940 (33·2%) | ·· |
| 25–<30 | 1835/6512 (28·2%) | 436/1572 (27·7%) | 1399/4940 (28·3%) | ·· |
| 30–<35 | 851/6512 (13·1%) | 234/1572 (14·9%) | 617/4940 (12·5%) | ·· |
| 35–<40 | 378/6512 (5·8%) | 109/1572 (6·9%) | 269/4940 (5·4%) | ·· |
| ≥40 | 62/6512 (1·0%) | 18/1572 (1·1%) | 44/4940 (0·9%) | ·· |
| Race or ethnicity | ·· | ·· | ·· | <0·0001 |
| Black | 4759/6427 (74·0%) | 1243/1564 (79·5%) | 3516/4863 (72·3%) | ·· |
| Asian | 1640/6427 (25·5%) | 312/1564 (19·9%) | 1328/4863 (27·3%) | ·· |
| Other | 28/6427 (0·4%) | 9/1564 (0·6%) | 19/4863 (0·4%) | ·· |
| Median gravidity (IQR) | 2 (1–3); n=6485 | 2 (1–3); n=1572 | 2 (1–3); n=4913 | <0·0001 |
| Gravidity | ·· | ·· | ·· | <0·0001 |
| 1 | 2435/6485 (37·5%) | 513/1572 (32·6%) | 1922/4913 (39·1%) | ·· |
| 2 | 1703/6485 (26·3%) | 397/1572 (25·3%) | 1306/4913 (26·6%) | ·· |
| 3 | 1062/6485 (16·4%) | 293/1572 (18·6%) | 769/4913 (15·7%) | ·· |
| ≥4 | 1285/6485 (19·8%) | 369/1572 (23·5%) | 916/4913 (18·6%) | ·· |
| Median parity (IQR) | 1 (1–2); n=3938 | 2 (1–3); n=1031 | 1 (1–2); n=2907 | 0·0012 |
| Parity | ·· | ·· | ·· | 0·019 |
| 0 | 343/3938 (8·7%) | 80/1031 (7·8%) | 263/2907 (9·0%) | ·· |
| 1 | 1725/3938 (43·8%) | 418/1031 (40·5%) | 1307/2907 (45·0%) | ·· |
| 2 | 908/3938 (23·1%) | 248/1031 (24·1%) | 660/2907 (22·7%) | ·· |
| 3 | 455/3938 (11·6%) | 139/1031 (13·5%) | 316/2907 (10·9%) | ·· |
| ≥4 | 507/3938 (12·9%) | 146/1031 (14·2%) | 361/2907 (12·4%) | ·· |
| Previous stillbirth | ·· | ·· | ·· | 0·63 |
| Yes | 217/3714 (5·8%) | 61/983 (6·2%) | 156/2731 (5·7%) | ·· |
| No | 3497/3714 (94·2%) | 922/983 (93·8%) | 2575/2731 (94·3%) | ·· |
| Previous pregnancy loss | ·· | ·· | ·· | 0·57 |
| Yes | 831/3910 (21·3%) | 211/1025 (20·6%) | 620/2885 (21·5%) | ·· |
| No | 3079/3910 (78·7%) | 814/1025 (79·4%) | 2265/2885 (78·5%) | ·· |
| Median maternal MUAC (IQR), cm | 27 (25–30); n=5633 | 28 (26–31); n=1274 | 27 (24–30); n=4359 | <0·0001 |
| Chorioamnionitis | ·· | ·· | ·· | 0·27 |
| Yes | 10/6489 (0·2%) | 4/1569 (0·3%) | 6/4920 (0·1%) | ·· |
| No | 6479/6489 (99·8%) | 1565/1569 (99·7%) | 4914/4920 (99·9%) | ·· |
| Single or multiple birth | ·· | ·· | ·· | 0·17 |
| Singleton | 6445/6514 (98·9%) | 1550/1572 (98·6%) | 4895/4942 (99·0%) | ·· |
| Twin | 69/6514 (1·1%) | 22/1572 (1·4%) | 47/4942 (1·0%) | ·· |
| Antimicrobials in urine | ·· | ·· | ·· | <0·0001 |
| Yes | 470/6227 (7·5%) | 77/1506 (5·1%) | 393/4721 (8·3%) | ·· |
| No | 5757/6227 (92·5%) | 1429/1506 (94·9%) | 4328/4721 (91·7%) | ·· |
| Bacteriuria† | ·· | ·· | ·· | <0·0001 |
| Yes | 435/4958 (8·8%) | 405/1162 (34·9%) | 30/3796 (0·8%) | ·· |
| No | 4523/4958 (91·2%) | 757/1162 (65·1%) | 3766/3796 (99·2%) | ·· |
| Number of births from which swabs were collected, n | 6567‡ | 1592 | 4975 | ·· |
| Mode of delivery§ | ·· | ·· | ·· | 0·25 |
| Vaginal | 5599/6562 (85·3%) | 1372/1591 (86·2%) | 4227/4971 (85·0%) | ·· |
| Caesarean | 963/6562 (14·7%) | 219/1591 (13·8%) | 744/4971 (15·0%) | ·· |
| Reason for caesarean¶ | ·· | ·· | ·· | >0·99 |
| Emergency | 842/963 (87·4%) | 192/219 (87·7%) | 650/744 (87·4%) | ·· |
| Elective | 121/963 (12·6%) | 27/219 (12·3%) | 94/744 (12·6%) | ·· |
| Median neonate birthweight (IQR), kg | 3·1 (2·8–3·4); n=6545 | 3·1 (2·8–3·4); n=1588 | 3·1 (2·8–3·4); n=4957 | 0·74 |
Data are n/N (%) unless otherwise specified. Denominators are the overall number of participants (with available data) in the group identified in the column heading. GBS=group B Streptococcus. MUAC=mid-upper arm circumference.
p value comparing categorical variables using Fisher’s exact test or χ2 test or comparing quantitative values using Wilcoxon rank sum test for the difference between the GBS positive and GBS negative groups.
Excludes participants from Ethiopia and Mali, since it was not possible to culture their urine samples.
There were 6583 births (6445 singletons and 69 sets of twins), from which 6567 swabs were collected (in 53 sets of twins both had a swab collected, and in 16 sets of twins only one infant had a swab collected).
For mode of delivery, the denominator is the total number of births from which swabs were obtained from the newborn, and for which data on mode of delivery were obtained.
For reason for caesarean, the denominator is total number of caesareans.