Gayatri Mantra is the most powerful mantra. This mantra helps to improve an intelligence of the person who chants. The Gayatri Mantra is the embodiment of all Gods.
Pregnant Ladies can chant Gayatri Mantra during pregnancy. When pregnant moms used to recite gayatri mantra throughout their pregnancy it will nurture genius nature and strong spiritual qualities in the child. The important thing you must consider is reciting Gayatri Mantra with proper pronouncing.
Gayatri Mantra :
OM BHUR BHUVA SUVAHAA
TAT SAVITUR VARENYAM
BHARGO DEVASYA DHEEMAHI
DHIYO YO NA PRACHOODAYAT