Fetal heart rate increasing?

Is it normal for fetal heart rate to increase slightly? Up until 21 weeks, my baby’s heart rate was trending downwards, but at 22 (and 23) weeks, it increased slightly. Is this normal or cause for concern?

162 bpm at 8 weeks

154 bpm at 12 weeks

146 bpm at 17 weeks

145 bpm at 21 weeks

154 bpm at 22/23 weeks