My remark; take B12 and folate[folic acid] and see further below:

Book : Human nutrition : M Barasi

Several features of the pre-pregnancy diet
may affect the chances of conception or the
success of pregnancy. For example:
vitamin D deficiency in adolescence may have
resulted in rickets with pelvic malformations,
making a normal delivery impossible;
■ a dietary deficiency of vitamin B12 may cause
infertility; and
■ a history of dieting, or in its extreme form
anorexia nervosa, can result in poor nutritional status, with low reserves of many
nutrients.
Research on underweight women has found
that low body fat stores are associated with
amenorrhoea and infertility.

Evidence of this association comes from records obtained in
wartime from places where food supplies were
critical, such as Holland and Leningrad, as well
as from more recent studies in infertility clinics
and on women with anorexia. These indicate
that a body mass index (BMI) of 20.8 appears to
be a threshold for normal pregnancy, and that
there is a minimum ratio of fat: lean body mass
needed to support pregnancy