Ultrasound Series: Part 3 Heartbeat

July 2, 2021

“Is that my baby’s heartbeat?” is a question that I hear almost every time I perform an ultrasound. The fetal (baby’s) heartbeat is an important indicator that everything is progressing as it should and a question that most parents want to be answered. At Crossroads, we feel that this is so important that all parents receive a picture of their baby’s heartbeat.

Appointments for this ultrasound are usually scheduled after 6 weeks gestational age (6 weeks after the first day of your last menstrual period). It is at this time that the baby is big enough to obtain this value. Even waiting until after 6 weeks, a transvaginal scan is required to measure the heartbeat of this tiny 6mm baby.

There’s an old wives tale that states that a boy baby’s heartbeat is usually slower than 140 beats per minute (bpm) and a girl baby’s heartbeat is usually faster than 140 bpm. This is an old wives’ tale. If your baby is active, its heart rate will be elevated. The baby’s gestational age also plays an important role in how fast a baby’s heart rate is.

The average baby’s heart rate is measured around 110 at around 6 weeks gestation, peaks at 9 weeks (sometimes reaching levels near 180 bpm), and then gradually decreases as the fetus approaches term. (1)

Sometimes the baby’s heart rate is slower, especially if it is very early in the pregnancy (before 7 weeks gestation). If this happens, a repeat ultrasound is scheduled within a couple of weeks of the first ultrasound to recheck the heart rate. This waiting period can be very stressful for the parents. Unfortunately, time is what is required—time for the baby to mature and grow. Babies grow very rapidly during this period in a pregnancy, but that will be addressed in the next blog.

This blog post is part three of our series about Ultrasounds, written by our Nurse Manager, Tresa: “Here at Crossroads Pregnancy Center, we offer free, limited obstetric ultrasounds. I would like to discuss what this means to our clients. I hope to accomplish this topic in a 4-part post.” Part 1 and Part 2 can be read here.