Crotch Pain During Pregnancy: Causes & Relief (20 Weeks)

Question
This may be an unusual question, but I am 29 yrs old, pregnant with my first child.  I am about 20 weeks now, the first day of my last period was Sep 1st.  Lately I have been having soreness in my crotch, like between my legs and my vagina on both sides.  It is usually when I'm sleeping, especially when on my back (which I try to avoid, I know about sleeping on the left side but I do wake up on my back occasionally) and goes away when I'm up and walking around.  I have no varicose veins, no one in my family does.  And it is not back by my rectum, I really don't think it is hemorroids.  Before I was pregnant I used to get a somewhat similar soreness like this with menstrual cramps (I get bad cramps, always have) but it was more mild and they would go away with Midol.  Do you think this could be because of stretching of the uterus?  Or less blood flow to the uterus because I'm on my back?  Is it normal?  I've also never had any type of STD in my life and have been with my husband for 8 and a half years.  And I don't think it is related to sex because we really aren't having much sex right now.  Like I had this last night, and we haven't had sex in over a week.  Any advice would be appreciated.  Thanks in advance.

Answer
If your last period started on September 1, you are now 19 weeks 3 days gestational age. It is common at this point in pregnancy to have "round ligament syndrome", which is pain in your groin due to stretching of the round ligaments (the ligaments that anchor the uterus to the sidewalls of the abdomen. The pain is a tearing or searing pain that is felt often upon getting out of bed or out of a chair or when suddenly turning while walking. Tylenol or heating pads or a warm shower will help alleviate the discomfort, and the pain should subside once the uterus grows into the abdomen from the pelvis (in a few weeks). Don't worry. It is normal.