Hi, yes i have to agree with Annie & spade22 - Blessings
Babies heart starts to beat about 18 days after conception but isnt typically detected by transvaginal US until 3-4 weeks after conception (5-6 weeks gestation).
Are you saying four weeks from your last period? If so, no. Are you saying four weeks from conception? Yes, since that would be considered six weeks pregnant, counted the medical way (in other words, from your first day of your last period).