In an 8-year Harvard study involving 18,555 married women, results showed that regular use of multivitamin supplements were associated with a reduced risk of ovulatory infertility. During 8 years of follow-up, 438 women reported infertility caused by ovulatory disorder. Women taking two or less multivitamin tablets per week showed a 12% reduced risk of ovulatory infertility, women taking three to five multivitamin tablets per weeks showed a 31% reduced risk, and women taking six or more multivitamin tablets per week showed a 41% reduced risk, compared to women who did not use multivitamin supplements. The association between frequency of multivitamin supplement use and risk of ovulatory infertility was partly explained by folic acid. The authors of this study conclude, "Regular use of multivitamin supplements may decrease the risk of ovulatory infertility."
I recommend a good multivitamin powder for overall nutritional support for both men and women.
"Use of multivitamins, intake of B vitamins, and risk of ovulatory infertility," Chavarro JE, Willett WC, et al, Fertil Steril, 2008; 89(3): 668-76.