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Search review questions
Each row is one question a systematic review asked: who, what, compared with what, and which outcome, with the effect it found and how certain that is. Words match anywhere in the field.
103 questions in 57 reviews
current versionsNo studies 4 · 3.9%Ungraded 9 · 8.7%Very low 19 · 18.4%Low 37 · 35.9%Moderate 20 · 19.4%High 14 · 13.6%
Ungraded means an effect was reported without a GRADE rating; it is not a gap. No studies means the review found nothing to answer the question. The six categories are a display order, not a score.
| Question | Effect | Evidence | Status / GRADE |
|---|---|---|---|
Outcomes for all interventions for smoking cessation in pregnancy vs control: subgrouped by main intervention strategy (comparison 20) Preterm birth (under 37 weeks) · Pregnant women who smoke Psychosocial interventions for supporting women to stop smoking in pregnancy (2017) · Cochrane | RR 0.93 [0.77, 1.11] | 19 studies · 9222 participants | High |
Intervention NR Preterm birth less than 34 weeks' gestation · women undergoing home monitoring for preventing preterm birth versus women receiving standard care Home uterine monitoring for detecting preterm labour (2017) · Cochrane | RR 0.78 [0.62, 0.99] | 3 studies · 1596 participants | High |
Intervention NR Preterm birth less than 37 weeks' gestation · women undergoing home monitoring for preventing preterm birth versus women receiving standard care Home uterine monitoring for detecting preterm labour (2017) · Cochrane | RR 0.85 [0.72, 1.01] | 8 studies · 4834 participants | Very low |
Cerclage vs no cerclage Preterm birth before 34 completed weeks · preventing preterm birth in women with singleton pregnancy Cervical stitch (cerclage) for preventing preterm birth in singleton pregnancy (2017) · Cochrane | RR 0.77 [0.66, 0.89] | 9 studies · 2415 participants | High |
Any supplement containing iodine vs same supplement without iodine or no treatment/placebo (maternal outcomes) Preterm birth · women during the preconception, pregnancy and postpartum period Iodine supplementation for women during the preconception, pregnancy and postpartum period (2017) · Cochrane | RR 0.71 [0.3, 1.66] | 2 studies · 376 participants | Low |
Intervention NR Very preterm birth (less than 34 weeks) ‐ assuming complete correlation between twins/triplets · women with multiple pregnancy Bed rest with and without hospitalisation in multiple pregnancy for improving perinatal outcomes (2017) · Cochrane | RR 1.02 [0.66, 1.58] | 5 studies · 495 participants | Low |
Intervention NR Very preterm birth (less than 34 weeks) ‐ assuming complete correlation between twins · women with multiple pregnancy Bed rest with and without hospitalisation in multiple pregnancy for improving perinatal outcomes (2017) · Cochrane | RR 2.3 [0.84, 6.27] | 1 study · 141 participants | Low |
Periodontal treatment (scaling and root planing, alone or with antimicrobials) vs Alternative (less intensive) periodontal treatment, alone or with placebo Preterm birth < 35 weeks · Pregnant women considered to have periodontal disease (gingivitis or periodontitis) after dental examination Treating periodontal disease for preventing adverse birth outcomes in pregnant women (2017) · Cochrane | Preterm births < 35 weeks reported in four studies across three subcomparisons; none of the subcomparisons showed a difference; SRP versus alternative mechanical treatment not pooled due to considerable heterogeneity;… | 4 studies | Very low |
Periodontal treatment (scaling and root planing, alone or with antimicrobials) vs Alternative (less intensive) periodontal treatment, alone or with placebo Gestational age (preterm birth < 37 weeks) · Pregnant women considered to have periodontal disease (gingivitis or periodontitis) after dental examination · SRP + antimicrobial vs SRP + placebo Treating periodontal disease for preventing adverse birth outcomes in pregnant women (2017) · Cochrane | RR 3.08 [1.15, 8.20] | 1 study · 243 participants | Very low |
SOF Immunological sealant vs standard care Preterm birth less than 37 weeks' gestation · preterm prelabour rupture of membranes (PPROM) Sealing procedures for preterm prelabour rupture of membranes (2016) · Cochrane | RR 0.48 [0.34, 0.68] | 1 study · 94 participants | Very low |
SOF Cervical adapter vs standard care Preterm birth less than 37 weeks' gestation · preterm prelabour rupture of membranes (PPROM) Sealing procedures for preterm prelabour rupture of membranes (2016) · Cochrane | no estimate extracted | 0 studies · 0 participants | Ungraded |
Acupuncture vs placebo Preterm birth less than 37 weeks · pregnant women with hyperemesis gravidarum Interventions for treating hyperemesis gravidarum (2016) · Cochrane | RR 0.12 [0.01, 2.26] | 1 study · 36 participants | Low |
Corticosteroids vs promethazine Preterm birth · Pregnant women with hyperemesis gravidarum Interventions for treating hyperemesis gravidarum (2016) · Cochrane | RR 3 [0.13, 69.52] | 1 study · 40 participants | Low |
Corticosteroids vs placebo Preterm birth · Pregnant women with hyperemesis gravidarum Interventions for treating hyperemesis gravidarum (2016) · Cochrane | RR 1.01 [0.31, 3.28] | 2 studies · 134 participants | Very low |
Balanced protein and energy supplementation vs control or no intervention Preterm birth · pregnant women Antenatal dietary education and supplementation to increase energy and protein intake (2015) · Cochrane | RR 0.96 [0.8, 1.16] | 5 studies · 3384 participants | Moderate |
Intervention NR Preterm birth · pregnant women Antenatal dietary education and supplementation to increase energy and protein intake (2015) · Cochrane | RR 1.14 [0.83, 1.56] | 1 study · 505 participants | Low |
Intervention NR Preterm birth · pregnant women Antenatal dietary education and supplementation to increase energy and protein intake (2015) · Cochrane | no estimate extracted | 0 studies · 0 participants | Ungraded |
Nutritional education vs no counselling or education during pregnancy Preterm birth · pregnant women Antenatal dietary education and supplementation to increase energy and protein intake (2015) · Cochrane | RR 0.46 [0.21, 0.98] | 2 studies · 449 participants | Low |
External cephalic version (ECV) commenced before term vs ECV at term Preterm birth < 37 weeks · women with breech presentation before term External cephalic version for breech presentation before term (2015) · Cochrane | RR 1.51 [1.03, 2.21] | 3 studies · 1888 participants | High |
Pyridoxine (B6) vs control Preterm birth (before 37 completed weeks of gestation) · pregnant women, either during the prenatal period or during labour. Pyridoxine (vitamin B6) supplementation during pregnancy or labour for maternal and neonatal outcomes (2015) · Cochrane | no estimate extracted | 0 participants | Ungraded |
Reduced number of antenatal care visits/goal‐oriented vs standard antenatal care visits Preterm birth · low‐risk pregnancy Alternative versus standard packages of antenatal care for low‐risk pregnancy (2015) · Cochrane | RR 1.02 [0.94, 1.11] | 7 studies · 53661 participants | Moderate |
All routine Doppler ultrasound vs no Doppler ultrasound Preterm birth (before 37 weeks) · Pregnant women in unselected or low‐risk populations. Fetal and umbilical Doppler ultrasound in normal pregnancy (2015) · Cochrane | RR 1.02 [0.86, 1.21] | 4 studies · 12162 participants | High |
Any vitamin E supplementation vs placebo, no placebo or other supplements Preterm birth (less than 37 weeks' gestation) · pregnant women receiving vitamin E supplementation or control, living in areas where there is either inadequate… Vitamin E supplementation in pregnancy (2015) · Cochrane | RR 0.98 [0.88, 1.09] | 11 studies · 20565 participants | High |
Intervention NR Preterm birth (< 37 weeks' gestation) · All pregnant women receiving either vitamin C supplementation or control either in areas where there is inadequate… Vitamin C supplementation in pregnancy (2015) · Cochrane | RR 0.99 [0.9, 1.1] | 16 studies · 22250 participants | High |
Oral betamimetic vs placebo Preterm birth (less than 37 weeks' gestation) · pregnant women with a twin pregnancy Prophylactic oral betamimetics for reducing preterm birth in women with a twin pregnancy (2015) · Cochrane | RR 0.85 [0.65, 1.1] | 4 studies · 276 participants | Low |
Oral betamimetic vs placebo Very preterm birth (less than 34 weeks' gestation) · pregnant women with a twin pregnancy Prophylactic oral betamimetics for reducing preterm birth in women with a twin pregnancy (2015) · Cochrane | RR 0.47 [0.15, 1.5] | 1 study · 144 participants | Low |
(Infant outcomes) Any supplements containing iron and folic acid vs same supplements without iron nor folic acid (no iron nor folic acid or placebo) Preterm birth (less than 37 weeks of gestation) (ALL) · Pregnant women of any gestational age and parity Daily oral iron supplementation during pregnancy (2015) · Cochrane | RR 1.55 [0.4, 6] | 3 studies · 1497 participants | Low |
(Infant outcomes) Any supplements containing iron vs same supplements without iron or no treatment/placebo (no iron or placebo) Preterm birth (less than 37 weeks of gestation) (ALL) · Pregnant women of any gestational age and parity Daily oral iron supplementation during pregnancy (2015) · Cochrane | RR 0.93 [0.84, 1.03] | 13 studies · 19286 participants | Moderate |
Specialised antenatal clinics vs standard care Very preterm birth (defined as birth less than 34 weeks' gestation) · Women with a multiple pregnancy for improving maternal and infant outcomes Specialised antenatal clinics for women with a multiple pregnancy for improving maternal and infant outcomes (2015) · Cochrane | no estimate extracted | NR | No studies |
Intervention NR Preterm birth (< 37 weeks gestation) (Any psychosocial intervention vs. control) Psychosocial interventions for pregnant women in outpatient illicit drug treatment programs compared to… (2015) · Cochrane | RR 0.71 [0.34, 1.51] | 3 studies · 264 participants | Moderate |
Lower genital tract infection screening vs no screening Preterm birth less than 37 weeks · pregnant women presenting for routine prenatal care Antenatal lower genital tract infection screening and treatment programs for preventing preterm delivery (2015) · Cochrane | RR 0.55 [0.41, 0.75] | 1 study · 4155 participants | Moderate |
Caffeinated (experimental group) vs decaffeinated group (control group) Preterm birth · Pregnant women recruited before 20 weeks' gestation Effects of restricted caffeine intake by mother on fetal, neonatal and pregnancy outcomes (2015) · Cochrane | RR 0.81 [0.48, 1.37] | 1 study · 1153 participants | Low |
Calcium supplementation vs placebo or no treatment (maternal outcomes) Preterm birth (a) Birth prior to 37 weeks · healthy pregnant women receiving calcium supplementation vs placebo or no treatment Calcium supplementation (other than for preventing or treating hypertension) for improving pregnancy and… (2015) · Cochrane | RR 0.86 [0.7, 1.05] | 13 studies · 16139 participants | Moderate |
Calcium supplementation vs placebo or no treatment (maternal outcomes) Preterm birth (b) Birth prior to 34 weeks · healthy pregnant women receiving calcium supplementation vs placebo or no treatment Calcium supplementation (other than for preventing or treating hypertension) for improving pregnancy and… (2015) · Cochrane | RR 1.04 [0.8, 1.36] | 4 studies · 5669 participants | Moderate |
All diet and/or exercise interventions vs standard/other care Preterm birth · pregnant women Diet or exercise, or both, for preventing excessive weight gain in pregnancy (2015) · Cochrane | RR 0.91 [0.68, 1.22] | 16 studies · 5923 participants | Moderate |
Group antenatal care vs individual antenatal care (adjusted data) Preterm birth (gestational age at time of birth less than 37 weeks' gestation) · pregnant women accessing prenatal care Group versus conventional antenatal care for women (2015) · Cochrane | RR 0.75 [0.57, 1] | 3 studies · 1888 participants | Moderate |
Intervention NR Preterm birth · Pregnant women Vitamin A supplementation during pregnancy for maternal and newborn outcomes (2015) · Cochrane | RR 0.39 [0.08, 1.93] | 1 study · 136 participants | Low |
Vitamin A alone vs placebo or no treatment Preterm birth · Pregnant women Vitamin A supplementation during pregnancy for maternal and newborn outcomes (2015) · Cochrane | RR 0.98 [0.94, 1.01] | 5 studies · 48007 participants | High |
Nitrofurantoin and close surveillance vs close surveillance alone Preterm birth (< 37 weeks) · pregnant women with a history of one or more UTI before or during pregnancy Interventions for preventing recurrent urinary tract infection during pregnancy (2015) · Cochrane | RR 1.18 [0.42, 3.35] | 1 study · 147 participants | Very low |
Micronutrient powders for point‐of‐use fortification of foods vs same multiple micronutrients Preterm births (births before 37 weeks of gestation) · women during pregnancy Multiple micronutrient powders for home (point‐of‐use) fortification of foods in pregnant women (2015) · Cochrane | no estimate extracted | 0 participants | Ungraded |
Micronutrient powders for point‐of‐use fortification of foods vs iron and folic acid supplements Preterm births (births before 37 weeks of gestation) · women during pregnancy Multiple micronutrient powders for home (point‐of‐use) fortification of foods in pregnant women (2015) · Cochrane | no estimate extracted | 0 participants | Ungraded |
Test of placental function vs standard care Preterm birth (before 37 weeks' gestation) reported gestation at birth · women in the third trimester of pregnancy Use of biochemical tests of placental function for improving pregnancy outcome (2015) · Cochrane | RR 2.9 [0.12, 69.81] | 1 study · 118 participants | Low |
Universal screening vs no screening Preterm birth · women during pregnancy Screening and subsequent management for thyroid dysfunction pre‐pregnancy and during pregnancy for improving… (2015) · Cochrane | no estimate extracted | NR | No studies |
Universal screening vs case finding Preterm birth · women during pregnancy Screening and subsequent management for thyroid dysfunction pre‐pregnancy and during pregnancy for improving… (2015) · Cochrane | RR 0.99 [0.8, 1.24] | 1 study · 4516 participants | High |
Intervention NR Preterm birth · Pregnant women (parity 0‐1) Drugs for preventing malaria in pregnant women in endemic areas: any drug regimen versus placebo or no… (2014) · Cochrane | RR 0.85 [0.66, 1.1] | 2 studies · 1493 participants | Low |
Intervention NR Preterm birth · Pregnant women (parity 2+) Drugs for preventing malaria in pregnant women in endemic areas: any drug regimen versus placebo or no… (2014) · Cochrane | no estimate extracted | 0 studies · 0 participants | Ungraded |
Intervention NR Preterm birth · Pregnant women (all parities) Drugs for preventing malaria in pregnant women in endemic areas: any drug regimen versus placebo or no… (2014) · Cochrane | RR 0.95 [0.65, 1.38] | 2 studies · 1174 participants | Low |
Intervention NR Preterm birth · Pregnant women (parity 0‐1) Drugs for preventing malaria in pregnant women in endemic areas: any drug regimen versus placebo or no… (2014) · Cochrane | RR 0.85 [0.66, 1.1] | 2 studies · 1493 participants | Low |
Intervention NR Utilisation of research (Thailand) (for six obstetric practices: social support during labour, magnesium sulphate for eclampsia, corticosteroids to women with preterm birth, selective episiotomy, antibiotic use at caesarean section and vacuum extr... · Healthcare decision makers, health system managers or policy makers Interventions to improve the use of systematic reviews in decision‐making by health system managers, policy… (2012) · Cochrane | no estimate extracted | NR | Moderate |
Intervention NR Utilisation of research (Mexico) (for six obstetric practices: social support during labour, magnesium sulphate for eclampsia, corticosteroids to women with preterm birth, selective episiotomy, antibiotic use at caesarean section and vacuum extrac... · Healthcare decision makers, health system managers or policy makers Interventions to improve the use of systematic reviews in decision‐making by health system managers, policy… (2012) · Cochrane | no estimate extracted | NR | Moderate |