BACKGROUND: It has been suggested that low serum zinc levels may be associated with suboptimal outcomes of pregnancy such as prolonged labour, atonic postpartum haemorrhage, pregnancy-induced hypertension, preterm labour and post-term pregnancies, although many of these associations have not yet been established. OBJECTIVES: To assess the effects of zinc supplementation in pregnancy on maternal, fetal, neonatal and infant outcomes. SEARCH METHODS: We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 October 2014) and reference lists of retrieved studies. SELECTION CRITERIA: Randomised trials of zinc supplementation in pregnancy. We excluded quasi-randomised controlled trials. DATA COLLECTION AND ANALYSIS: Three review authors applied the study selection criteria, assessed trial quality and extracted data. When necessary, we contacted study authors for additional information. The quality of the evidence was assessed using GRADE. MAIN RESULTS: We included 21 randomised controlled trials (RCTs) reported in 54 papers involving over 17,000 women and their babies. One trial did not contribute data. Trials were generally at low risk of bias. Zinc supplementation resulted in a small reduction in preterm birth (risk ratio (RR) 0.86, 95% confidence interval (CI) 0.76 to 0.97 in 16 RCTs; 16 trials of 7637 women). This was not accompanied by a similar reduction in numbers of babies with low birthweight (RR 0.93, 95% CI 0.78 to 1.12; 14 trials of 5643 women). No clear differences were seen between the zinc and no zinc groups for any of the other primary maternal or neonatal outcomes, except for induction of labour in a single trial. No differing patterns were evident in the subgroups of women with low versus normal zinc and nutrition levels or in women who complied with their treatment versus those who did not. The GRADE quality of the evidence was moderate for preterm birth, small-for-gestational age, and low birthweight, and low for stillbirth or neonatal death and birthweight. AUTHORS' CONCLUSIONS: The evidence for a 14% relative reduction in preterm birth for zinc compared with placebo was primarily represented by trials involving women of low income and this has some relevance in areas of high perinatal mortality. There was no convincing evidence that zinc supplementation during pregnancy results in other useful and important benefits. Since the preterm association could well reflect poor nutrition, studies to address ways of improving the overall nutritional status of populations in impoverished areas, rather than focusing on micronutrient and or zinc supplementation in isolation, should be an urgent priority.
BACKGROUND: It has been suggested that low serum zinc levels may be associated with suboptimal outcomes of pregnancy such as prolonged labour, atonic postpartum haemorrhage, pregnancy-induced hypertension, preterm labour and post-term pregnancies, although many of these associations have not yet been established. OBJECTIVES: To assess the effects of zinc supplementation in pregnancy on maternal, fetal, neonatal and infant outcomes. SEARCH METHODS: We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 October 2014) and reference lists of retrieved studies. SELECTION CRITERIA: Randomised trials of zinc supplementation in pregnancy. We excluded quasi-randomised controlled trials. DATA COLLECTION AND ANALYSIS: Three review authors applied the study selection criteria, assessed trial quality and extracted data. When necessary, we contacted study authors for additional information. The quality of the evidence was assessed using GRADE. MAIN RESULTS: We included 21 randomised controlled trials (RCTs) reported in 54 papers involving over 17,000 women and their babies. One trial did not contribute data. Trials were generally at low risk of bias. Zinc supplementation resulted in a small reduction in preterm birth (risk ratio (RR) 0.86, 95% confidence interval (CI) 0.76 to 0.97 in 16 RCTs; 16 trials of 7637 women). This was not accompanied by a similar reduction in numbers of babies with low birthweight (RR 0.93, 95% CI 0.78 to 1.12; 14 trials of 5643 women). No clear differences were seen between the zinc and no zinc groups for any of the other primary maternal or neonatal outcomes, except for induction of labour in a single trial. No differing patterns were evident in the subgroups of women with low versus normal zinc and nutrition levels or in women who complied with their treatment versus those who did not. The GRADE quality of the evidence was moderate for preterm birth, small-for-gestational age, and low birthweight, and low for stillbirth or neonatal death and birthweight. AUTHORS' CONCLUSIONS: The evidence for a 14% relative reduction in preterm birth for zinc compared with placebo was primarily represented by trials involving women of low income and this has some relevance in areas of high perinatal mortality. There was no convincing evidence that zinc supplementation during pregnancy results in other useful and important benefits. Since the preterm association could well reflect poor nutrition, studies to address ways of improving the overall nutritional status of populations in impoverished areas, rather than focusing on micronutrient and or zinc supplementation in isolation, should be an urgent priority.
Authors: A Kirksey; A Rahmanifar; T D Wachs; G P McCabe; N S Bassily; Z Bishry; O M Galal; G G Harrison; N W Jerome Journal: Am J Clin Nutr Date: 1991-10 Impact factor: 7.045
Authors: I F Hunt; N J Murphy; A E Cleaver; B Faraji; M E Swendseid; B L Browdy; A H Coulson; V A Clark; R H Settlage; J C Smith Journal: Am J Clin Nutr Date: 1985-11 Impact factor: 7.045
Authors: E Villamor; S Aboud; I N Koulinska; R Kupka; W Urassa; B Chaplin; G Msamanga; W W Fawzi Journal: Eur J Clin Nutr Date: 2006-02-01 Impact factor: 4.016
Authors: Mario Merialdi; Laura E Caulfield; Nelly Zavaleta; Alberto Figueroa; Kathleen A Costigan; Francesca Dominici; Janet A Dipietro Journal: Am J Clin Nutr Date: 2004-05 Impact factor: 7.045
Authors: A Kirksey; T D Wachs; F Yunis; U Srinath; A Rahmanifar; G P McCabe; O M Galal; G G Harrison; N W Jerome Journal: Am J Clin Nutr Date: 1994-11 Impact factor: 7.045
Authors: Tormod Rogne; Myrte J Tielemans; Mary Foong-Fong Chong; Chittaranjan S Yajnik; Ghattu V Krishnaveni; Lucilla Poston; Vincent W V Jaddoe; Eric A P Steegers; Suyog Joshi; Yap-Seng Chong; Keith M Godfrey; Fabian Yap; Raquel Yahyaoui; Tinku Thomas; Gry Hay; Marije Hogeveen; Ahmet Demir; Ponnusamy Saravanan; Eva Skovlund; Marit P Martinussen; Geir W Jacobsen; Oscar H Franco; Michael B Bracken; Kari R Risnes Journal: Am J Epidemiol Date: 2017-02-01 Impact factor: 4.897
Authors: Anne Marie Darling; Ferdinand M Mugusi; Analee J Etheredge; Nilupa S Gunaratna; Ajibola Ibraheem Abioye; Said Aboud; Christopher Duggan; Robert Mongi; Donna Spiegelman; Drucilla Roberts; Davidson H Hamer; Kevin C Kain; Wafaie W Fawzi Journal: Am J Trop Med Hyg Date: 2017-01-23 Impact factor: 2.345
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Authors: Alison D Gernand; Kerry J Schulze; Christine P Stewart; Keith P West; Parul Christian Journal: Nat Rev Endocrinol Date: 2016-04-01 Impact factor: 43.330