The objective of the review is to use individual participant data (IPD) meta-analysis to explore the effect of mass deworming during pregnancy. We developed a search strategy and searched the databases till March 2018. We included individually randomised controlled trials; cluster randomised controlled trials and quasi randomised studies providing preventive or therapeutic deworming drugs for soil transmitted helminthiases and schistosomiasis during pregnancy. All IPD were assessed for completeness, compared to published reports and entered into a common data spreadsheet. Out of the seven trials elgible for IPD, we received data from three trials; out of 8,515 potential IPD participants; data were captured for 5,957 participants. Findings from this IPD suggest that mass deworming during pregnancy reduces maternal anaemia by 23% (Risk ratio [RR]: 0.77, 95% confidence intreval [CI]: 0.73–0.81; three trials; 5,216 participants; moderate quality evidence). We did not find any evidence of an effect of mass deworming during pregnancy on any of the other outcomes. There was no evidence of effect modification; however these findings should be interpreted with caution due to small sample sizes. The quality of evidence was rated as moderate for our findings. Our analyses suggest that mass deworming during pregnancy is associated with reducing anaemia with no evidence of impact on any other maternal or pregnancy outcomes. Our analyses were limited by the availability of data for the impact by subgroups and effect modification. There is also a need to support and promote open data for future IPDs.