Abstract: We included nine RCTs involving 725 women. However, five trials did not contribute data. Four trials involving 358 women contributed data. Trials were generally at mixed risk of bias. We only identified data for three comparisons: pharmaceutical treatment versus placebo or no treatment; acupuncture versus no treatment and pharmacological intervention versus advice on dietary and lifestyle changes. Pharmaceutical treatment compared with placebo or no treatment Two trials evaluated any pharmaceutical treatment compared with placebo or no treatment. One trial examined a treatment rarely used nowadays (intramuscular prostigmine 0.5 mg versus placebo). One trial evaluated the effect of magnesium and aluminium hydroxide plus simethicone liquid and tablet compared with placebo. For the primary outcome of this review (relief of heartburn), women who received pharmaceutical treatment reported complete heartburn relief more often than women receiving no treatment or placebo (risk ratio (RR) 1.85, 95% confidence interval (CI) 1.36 to 2.50 in two RCTs of 256 women, I2 = 0%, moderate-quality evidence). Data on partial relief of heartburn were heterogenous and showed no clear difference (average RR 1.35, 95% CI 0.38 to 4.76 in two RCTs of 256 women, very low-quality evidence). In terms of secondary outcomes, there was no clear difference in the rate of side effects between the pharmaceutical treatment group and the placebo/no treatment group (RR 0.63, 95% CI 0.21 to 1.89 in two RCTs of 256 women, very low-quality evidence). Pharmacological intervention versus advice on dietary and lifestyle choices One study compared 1 g of sucralfate with advice on dietary and lifestyle choices in treating heartburn. More women in the sucralfate group experienced complete relief of heartburn compared to women who received advice on diet and lifestyle choices (RR 2.41, 95% CI 1.42 to 4.07; participants = 65; studies = one). The only secondary outcome of interest addressed by this trial was side effects. The evidence was not clear on intervention side effects rate between the two groups (RR 1.74, 95% CI 0.07 to 41.21; participants = 66; studies = one). There was only one instance of side effects in the pharmacological group. Acupuncture compared with no treatment One trial evaluated acupuncture compared with no treatment but did not report data relating to this review's primary outcome (relief of heartburn). In terms of secondary outcomes, there was no difference in the rate of side effects between women who had acupuncture and women who had no treatment (RR 2.43, 95% CI 0.11 to 55.89 in one RCT of 36 women). With regard to quality of life, women who had acupuncture reported improved ability to sleep (RR 2.80, 95% CI 1.14 to 6.86) and eat (RR 2.40, 95% CI 1.11 to 5.18 in one RCT of 36 women). The following secondary outcomes were not reported upon in any of the trials included in the review: miscarriage, preterm labour, maternal satisfaction, fetal anomalies, intrauterine growth restriction, low birthweight. There are no large-scale RCTs to assess heartburn relief in pregnancy. This review of nine small studies (which involved data from only four small studies) indicates that there are limited data suggesting that heartburn in pregnancy could be completely relieved by pharmaceutical treatment. Three outcomes were assessed and assigned a quality rating using the GRADE methods. Evidence from two trials for the outcome of complete relief of heartburn was assessed as of moderate quality. Evidence for the outcomes of partial heartburn relief and side effects was graded to be of very low quality. Downgrading decisions were based in part on the small size of the trials and on heterogenous and imprecise results. There are insufficient data to assess acupuncture versus no treatment and no data to assess other comparisons (miscarriage, preterm labour, maternal satisfaction, fetal anomalies, intrauterine growth restriction, low birthweight). Further RCTs are needed to fully evaluate the effectiveness of interventions for heartburn in pregnancy. Future research should also address other medications such as histamine 2-receptor antagonists, promotility drugs, proton pump inhibitors, and a raft-forming alginate reflux suppressant in treatment of heartburn in pregnancy. More research is needed on acupuncture and other complimentary therapies as treatments for heartburn in pregnancy. Future research should also evaluate any adverse outcomes, maternal satisfaction with treatment and measure pregnant women's quality of life in relation to the intervention.

Plain-language summary: We found four small trials that provided data on 358 women. We estimated that the risk of bias was low for women enrolled in the study and the researchers as far as knowing if they were in the treatment group or the control (or placebo) group. It was unclear if there was a risk of bias for how the decisions were made to for women to be in the treatment or control/placebo groups, for those looking at the results and if all the results were reported. Two trials looked at medication compared with placebo or no treatment. One study examined the effect of a medication(sucralfate) in comparison to advice on dietary and lifestyle choice. One trial evaluated acupuncture versus no treatment. Women who received medication reported complete relief from heartburn more often than women receiving no treatment or placebo, or women who received advice on diet and lifestyle choices (moderate quality of evidence). We found no difference in partial relief of heartburn nor in side effects between the treatment groups (very low quality of evidence). We also found women who received acupuncture reported improved quality of life in terms of improved ability to sleep and eat, and no difference in the rate of side effects compared to women who received no acupuncture, From the little evidence there is, medication seems to help relieve heartburn but there is not enough data to say which medication is best. Acupuncture seems to help women to eat and sleep better when troubled with heartburn. Further research is needed to fully evaluate the effectiveness of interventions for heartburn in pregnancy. Future research should also address other medications such as histamine 2-receptor antagonists, promotility drugs, proton pump inhibitors, and a raft-forming alginate reflux suppressant in treatment of heartburn in pregnancy. More research is needed on acupuncture and other complimentary therapies as treatments for heartburn in pregnancy. Future research should also consider any adverse outcomes, maternal satisfaction with treatment and measure pregnant women's quality of life in relation to the intervention.