Mantra for pregnancy in Hinduism is dedicated to Dhanwantari. The mantra should be chanted in the morning hours after sunrise. Here is the mantra for pregnancy.
श्री धनवंतरी स्वरूप श्री
श्री श्री औषधचक्त्र
नारायणाय नमः॥
Sri Dhanwantari Swaroopa Sri Sri Sri Oushadachakra narayanaya namah
Sri Dhanwantari Swaroopa Sri Sri Sri Oushadachakra narayanaya namah
The mantra should be chanted 108 times facing the sun.
Feeding cow, ants, fishes, birds and other animals helps in solving pregnancy related problems.
It is also highly meritorious to plant trees and take care of them like children. All these actions along with the mantra help in creating a positive aura. This positive energy helps in giving birth at the earliest.