関連ワード:  when does baby heart beat slow down    when do babies heart beats slow down    when does baby heart rate slow down after birth    when does baby heart rate slow down in womb    when does newborn heart rate slow down    when does a child's heart rate slow down    when do babies heart rates slow down in the womb    does baby heart rate slow down when sleeping in womb    does baby's heart rate slow down in second trimester    does baby's heart rate slow down before labor