Maybe after birth women do lose some tightness, but that's also after having sex. Those men who are so concerned with their women being loose, isn't actually concerned about their women beiong loose. In other words, they become so insecure about their penis size, that that becomes their main focus. So to make themselves feel better about their insecurities, they blame their women.
I've been with single mother's before, even one who had more than 4 children, and let me tell you....."it feels so good!!" Hahaha. And it doesn't feel good because they know what they're doing, but becuase I rather not be insecure about my size and just enjoy the sex life my gf and I have. Let's be truthful and face the facts....most men are selfish lovers. They just want to get their nut on and go one with their lives. But if you knew what to do, children or not, sex with a woman is still very enjoyable for her, and to me.
Stop focusing on how small or big your D1ck is, and focus on making it enjoyable.