It's not only about respect towards women, his mother or generally mother nature. If he's respectful and polite, it's already a good thing. But there are other informations that he might need to know.
It would be great if she could use a helping hand to carry heavy items from the supermarket or somebody who would give up the place on public transport and she doesn't need to stand for so long. Unfortunately these days some men don't even show respect. Other day I was looking a middle-age man on the Piccadilly line reading his newspaper, while a pregnant lady was standing next to him wearing a huge badge “Baby on board” But even without the badge you could tell she's expecting a baby. He looked at her and.. continued reading his newspaper. No reaction. Maybe she should has stood up for herself and the health of her body and just ask him – or anybody – to give up the place for her. Luckily a young student girl was more eagle. If the woman unaware of these information and she doesn't take care of her own body, thinking "I can stand" or "it's not so heavy", these muscles may also be damaged and it can cause urinary incontinence, cystocele or the prolapse of the uterus. A pelvic surgery might be needed. No, we, women don't like that! So please next time when you see an expecting lady, offer your seat relaxing her pelvic muscles and make her day better and she can believe gentlemen still exist!