Table.
Study characteristics of case–control and cohort studies
| Case-control studies | ||||||||
|---|---|---|---|---|---|---|---|---|
| Author, y; study year, country, data source | Facility | Study population | Confounders | Oxytocin | Outcome | Exposed cases/all cases | Exposed controls/all controls | Effect estimate |
| Delaney et al,20 2021a; 2014–2017, India. DO (oxytocin and bag-mask). MR (stillbirths and oxytocin). IN (perinatal mortality). |
30 facilities: 8 primary health centers; 18 community health centers; 4 first referral units. | All women admitted to a study facility for childbirth (stillbirths and bag-mask). All women with known health outcomes (perinatal mortality). | Not adjusted | 32%–78%. Intramuscular injections |
Perinatal mortality, not defined | 1597/87 | 1265/47 | OR, 1.47 (0.99–2.16) |
| Bag-and-mask ventilation | 3291/247 | 2193/44 | OR, 3.74 (2.37–5.90) | |||||
| Stillbirths | Numbers not available | Numbers not available | No difference (numbers not available) | |||||
| Litorp et al,21 2021a; 2017–2018, Nepal. MR. | 12 public referral hospitals. | All women excluding women with elective CD (5.4%), missing data on augmentation of labor (15%), and absent or no recording of FHR on admission (3.7%). | Multivariate logistic regression adjusted for parity, induction, maternal age, GA, complications during pregnancy or labor, BW, suboptimal partograph use, suboptimal FHR monitoring, ethnicity, educational level, and mode of delivery. |
37%. Gravity-fed infusion or electronic infusion pumps. |
All | All exposed: 28,915 (applies to all outcomes) | All unexposed: 50,016 (applies to all outcomes) | aRR |
| Stillbirths and day-1 neonatal mortality | 64 | 130 | 1.24 (0.65–2.40) | |||||
| Neonatal death at discharge | 234 | 422 | 1.93 (1.46–2.56) | |||||
| 5-min Apgar <7 | 1136 | 1553 | 1.65 (1.49–1.86) | |||||
| Bag-and-mask ventilation | 439 | 346 | 2.10 (1.80–2.50) | |||||
| ECD | 356 | 968 | 0.62 (0.59–0.66) | |||||
| Postpartum hemorrhage | 67 | 155 | 0.80 (0.55–1.20) | |||||
| Dujardin et al,22 1995a; 1990–1991, Benin, Democratic Republic of the Congo, and Senegal. DO. | 8 peripheral maternity clinics and 2 reference hospitals. | All women, <10 cm dilated, singleton, vertex, BW >1000 g. | Multivariate logistic regression adjusted for primiparity, previous complicated delivery, presence of meconium during labor, ruptured membranes, education. | Benin: 21%; Senegal: 11%; Congo: 6%. Gravity-fed infusion. |
Stillbirths (analysis restricted to oxytocin applied in normally progressing labor) | 279/16 | 2131/53 | RR, 1.9 (1.06–3.40) |
| Manual respiratory assistance | 266/76 | 2069/206 | aOR, 2.88 (1.84–4.50)b | |||||
| Mola and Rageau,23 1990a; 1989, Papua New Guinea. DO. | General hospital. | All women in spontaneous labor, singleton, vertex. Cases: oxytocin augmentation. Controls: next delivery with same parity. |
Not adjusted, but matching was done on parity, and only women in spontaneous labor were included. | 10.3%. Gravity-fed infusion, no infusion pumps available. | Stillbirths, intrapartum or neonatal death not defined | 329/3 | 329/2 | RR, 1.50 (0.25–8.92) |
| 5-min Apgar £6 | 329/1 | 329/1 | RR, 1 (0.06–16.6) | |||||
| Case–control studies | ||||||||
| Author, y; study year, country, data source (variable) | Facility | Study population | Confounders | Oxytocin | Outcome | Exposed cases/all cases | Exposed controls/all controls | Effect estimate |
| Mohan et al,24 2020a; 2008–2010b, India. IN. | All facility births in India. | Cases: neonatal day-1 mortality. Controls: death between day 8 and 28 (late neonatal deaths). |
Adjusted for the presence of skilled birth attendant. Stratified by sex and parity. The following were included in a supplementary adjusted analysis with 2% difference in point estimate: age, multiple pregnancy, APH, prolonged laborc, foul smelling amniotic fluid, PROM, cord prolapse, preterm, assisted deliveries, malpresentation, fever on the day delivery began, received ANC. | Cases: 74%. Controls: 62%. Intramuscular injections. |
Neonatal day-1 mortality | Government hospitals: 212/28 Private hospitals: 672/792 |
51/67 127/166 |
aOR, 0.96 (0.59–1.6) aOR, 1.8 (1.2–2.5) |
| Ellis et al,25 2000; 1995–1996, Nepal. DO. | Principal maternity hospital. | GA >37. Cases: NE. Controls: unmatched, every 25th infant. Excluding congenital malformations, hepatosplenomegaly, cataracts, signs of infection, infants who normalized after hypoglycemia was corrected. |
Adjusted for maternal age, parity, education, height, previous neonatal death, antenatal care, preeclampsia, BW, sex of infant, and plurality. No infants were >4 kg. Balance between groups for prolonged labor. | Cases: 39%. Controls: 22%. Administration not described. |
NE within 24 h,Amiel–Tison score assessed by trained Junior doctors | 50/131 | 139/635 | aOR, 3.51 (2.04–6.07) |
| Tann et al,26 2018; 2011–2012, Uganda. MR. | Referral hospital. | GA >27. Cases: NE. Controls: unmatched, Thompson score <3, recruited in a ratio of 79:21 from high-risk and low-risk wards, respectively. Excluding antibiotics given, mothers living 20 km away, out-born infants. |
Adjusted for primiparity, socioeconomic group, age >20 y, weight <50 kg, height <150 cm, >4 ANC visits, sex, previous birth asphyxia, previous perinatal death, severe anemia, hypertension, HIV, sex, BW, twins, noncephalic, no IAS of FHR during labor, prolonged rupture of membranes >24 h, obstructed labor. Balance between the groups for prolonged labor.c | Controls: 10.5%. Cases: 20.1%. Administration not described. |
NE: Thompson score >5 within 12 h assessed by the author or other study doctors |
42/209 | 43/408 | aOR, 2.23 (1.17–4.23) |
| Maaløe et al,27 2016; 2014–2015, Tanzania. MR. | Tertiary referral hospital. | Singleton, BW ³2 kg, positive FHR on admission. Cases: stillbirths. Controls: unmatched, Apgar ≥7, every 10th delivery, ratio 1:4. |
Not adjusted. Balance between the 2 groups for induction and parity. More cases crossed the partograph alert and action line than controls. | Cases: 36%. Controls: 23%. Infusion, not further specified. |
Stillbirths with positive FHR on admission | 26/72 | 58/249 | OR, 1.86 (1.06–3.27) |
| Onyearugha and Ugboma,28 2010; 2004, Nigeria. DO (Apgar score), MR (oxytocin). | Tertiary hospital, serving both as a secondary healthcare center and referral center for peripheral hospitals. | Cases: severe birth asphyxia. Controls: same weight bracket, Apgar 8–10, consecutively recruited. Excluding severe congenital malformation. |
Not adjusted. Prolonged labor was more common in cases than in controls. | Cases: 7%. Controls: 5%. Administration not described. |
Apgar 1–3 at 1 min and <5 at 5 min, assessed by the author or a resident | 7/98 | 5/98 | OR, 1.43 (0.44–4.67) |
| Hailu et al,29 2018; 2018 Ethiopia. MR. | 5 hospitals (2 governmental and 3 private). | Cases: infants with asphyxia. Controls: unmatched, ratio 1:4. |
Not adjusted. Balance between the 2 groups for parity. Labor duration >12 h was more common in cases than in controls. | Cases: 10.5%. Controls: 12.5%. Administration not described. |
Asphyxia: inability to sustain adequate respiration with an Apgar <7 at 5 min, assessed by trained midwives | 8/76 | 38/296 | OR, 0.80 (0.36–1.79) |
| Geelhoed et al,30 2015; 2009–2011, Mozambique. MR. | 2 urban health centers (providing basic emergency obstetrical care) and 1 provincial hospital (providing comprehensive emergency obstetrical care). | Cases: stillbirths with GA >28 wk and BW >1.5 kg; 33% had positive FHR on arrival. Controls: live births matched on health facility attended, maternal age, and parity. First subsequent delivery. |
Not adjusted. Active first stage of labor >6 h was more common in cases than in controls. | Cases: 2%. Controls: 2.7% Intravenous infusion, not further specified. |
Stillbirths (including prefacility stillbirths) | 3/150 | 8/300 | OR, 0.81 (0.31–2.16) |
ANC, antenatal care; aOR, adjusted odds ratio; APH, antepartum hemorrhage; aRR, adjusted risk ratio; BW, birthweight; CD, cesarean delivery; DO, direct observations; ECD, emergency cesarean delivery; FHR, fetal heart rate; GA, gestational age; IAS, intermittent auscultation; IN, interviews; MR, medical records; NE, neonatal encephalopathy; OR, odds ratio; PROM, prelabor rupture of membranes; RR, risk ratio.
a
Studies with an objective of assessing the association between oxytocin augmentation and perinatal outcomes
b
Combined OR including OR from the 4 countries is calculated using RevMan 5.3, inverse variance outcome
c
Defined as labor duration >12 hours for multiparous women and >24 hours for nulliparous women.
Lauridsen Kujabi. A systematic review of oxytocin augmentation in low- and lower-middle-income country. Am J Obstet Gynecol Glob Rep 2022.