This is because vitamin levels usually take several months to establish, so you need to take them continuously during this period.

Once pregnant, you should continue to take a multivitamin containing folate and vitamin D as recommended by the UK Department of health.
Taking folate supplements during breastfeeding can also help, as your breastfeeding diet may not provide adequate nutrition.
Magnafolate® L-Methylfolate—maximizes the supplementation delivering a "finished" folate the body can immediately use without any kind of metabolization.
Jinkang Pharma ,the Manufacturer & Supplier of L Methylfolate.