Try not to have sex at the same time as your menstrual cycle would have been if you hadnt gotten pregnant.
At least for the first few months.
I have 3 live birth, but had 6 miscarriages of my own.
I remember getting to the emergency room thinking I was only just over 3 months, finding I was atleast 4 months (had a period with it)
hearing the heart beat and then days later delivering a living baby boy of only approx. 1 lb and 10 ozs. They told me they could not do anything for him, he was alive, inadiquate hospital for his age.
This all came about after a night of mad passionate love to my husband, it was our wedding anniversary.
Just try to hold off around the days you would have menstrated before you conceived it may be life saving for your baby.