There’s no need of contraceptive method. If one is trained up to indulge in sex only for begetting nice children, there is already contraceptive method. There is no necessity of unnecessarily producing cats and dogs children. So that requires training, determination. So sastra says you should not become father if you cannot train up your children to save him from death. Who is the father who’s training? To save him from the cycle of birth and death means to make him Krsna conscious. So if you are not yourself Krsna conscious, how you can train up your children to become Krsna conscious?

This is determination, that “If I cannot train my children to become Krsna conscious and thus avoid the botheration of birth and death, I shall not have sex.” That determination will save so many troubles. That can be done by practice.

That stage is possible. Still there are so many brahmacaris. Everything depends on practice. Abhyasa yoga-yuktena [Bg. 8.8]. That requires determination.

(Srila Prabhupada —  June 23, 1976, New Vrindavan)