Hello, and I hope I can help you today.
It is true that in late
pregnancy, the vagina begins to expand in order to prepare for birth. However, in the first trimester, there isn't really any degree of significant physical change of the vagina that would affect your husband's sensation.
However, is extremely common for men to feel uncomfortable or fearful of having intercourse with their wife when she is pregnant. Sometimes it is due to a misconception that sex can in some way hurt the baby your pregnancy, or that somehow the baby can "no" what's going on or somehow see or feel when his parents are having sex. Many men have trouble verbalizing these fears, and instead have other excuses or explanations for their unwillingness to perform intercourse.
Way to help to dispel these myths if possible, is to bring your husband with you to your prenatal appointment and ask your doctor in his presence if it is safe for you and the baby to be having sex. Sometimes hearing an explanation from a doctor can ease the peace of mind of a male partner who is ambivalent about sexual activity. Furthermore, non-intercourse sexual contact can also be used as an alternative if your husband would feel more comfortable that way.
Again, I encourage discussion with your local physician, but perhaps my answer will help aid in discussion with your husband in the meantime.
I hope I was able to adequately answer your question today, and that my advice was helpful.
Best wishes for the rest of the pregnancy,
Dr. Brown