Again, there is no substantial proof yet to prove which of the currently used vaccines may be better suited, or less harmful for pregnant women.
The major vaccines being used right now include Moderna Therapeutics Inc., Oxford-Astrazeneca (Covishield), Pfizer-BionTech, Covaxin, Sinopharm vaccine.
Different vaccine may carry different risks, depending on their type. While Covaxin and Covishield are traditional vaccines, made like influenza vaccines, Moderna and Pfizer make use of mRNA technology, which may be a little riskier. Both the companies are also currently running trials on pregnant women, so further research will be required to conclude which vaccine is safer or not.