Hi Mums. I'm eight weeks and five days pregnant and had an early scan today due to my long history of miscarriage. Baby had a heartbeat but measuring only six weeks and six day. That's 18 days of a difference. I know my dates are right and with a very uneventful sex life I know when it happened. I'm back in two weeks for another scan but I'm so upset. My heart is broken and I can't stay positive. Has anyone gone through this and had everything turn out okay? 18 days is a lot to be out by. Thanks.
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Expert advice on baby measuring small from a sonographer:
We often see patients for early pregnancy scans in our private clinics where the ultrasound dates don’t match up with the last menstrual period dates. Conception dates do not necessarily always happen on day 14 of the cycle, although it sounds like you are pretty sure of when it happened.
However, there are other features on the ultrasound that can give us an idea about viability. According to the HSE’s Clinical Practice Guideline for Ultrasound Diagnosis of Early Pregnancy Miscarriage, there are certain ultrasound features which predict, but are not diagnostic of, early pregnancy failure.
These include a foetal heart rate of less than 85 beats per minute at greater than seven weeks gestation, a small sac size relative to the embryo (difference of less than 5 mm between gestation sac and crown rump length), enlarged or abnormally shaped yolk sac and subchorionic haematoma.
The latter leads to a pregnancy loss rate of about 9%. This risk would appear to be increased in women older than 35 years and in pregnancies less than eight weeks gestation.
In your particular case, the embryo’s little heart is beating but the dates are not matching up with what you had in mind.
A follow-up scan is definitely necessary to assess for growth during those two weeks and to re-evaluate the heart rate. If the heart was beating at over 100bpm at your first scan and there were no other worrisome features as mentioned above on your first ultrasound, there is a 97% chance of a normal outcome of your pregnancy.
Hang in there and be kind to yourself while you wait for a definitive answer from the next scan.
Mums’ advice
Louise: My baby measured the same at the same weeks as you. He ended up arriving 12 days over and weighed 9lb 3oz. It depends what way the baby is moving. Try to relax as best you can. It’s hard waiting. I went for a private scan after a week to ease my mind and all was okay he measured to the correct dates. We went back to the hospital at the two weeks as agreed and he was still measuring a week and half behind.
Alisha: One very important thing to remember is that when you test positive, you are labelled as being four weeks pregnant. The reality is, you can't be as they are going from the first day of your last period, when you obviously weren't pregnant. You know what sex caused the pregnancy, but you don't (I presume) know the date you ovulated (sperm can live for five-ish days) and you wouldn't know the date of implantation either (this can happen two whole weeks after you ovulate, literally right before a period is due!).
Keeping this in mind, it's possible that the dates they give you can be a whole 14 days off, which is why most hospitals let you go two weeks ‘overdue’ before they act. It's possible (and I say possible, because I wouldn't like to get anyone's hopes up) that your baby is measuring just fine for when they implanted, which is when the pregnancy really starts. Just try to relax and see how things go.
Monica: This pregnancy, the baby was measuring two and a half weeks behind too, went for a scan two weeks later, the baby had grown two weeks growth. Another scan two weeks later and the baby had grown as required again, so it turns out my dates must have been later. Currently 17 weeks and growing no issues.
Jackie: After trying for three and a half years, I finally fell pregnant but had to go for an early scan due to severe cramps. My baby was reading six weeks, two days but I knew with the certainty that comes with charting my cycle for years exactly how far along I was eight weeks. The obgyn told me not to get too excited as it was early days, but I went back two weeks later and he was after catching up. He was 8lb at birth and now a 6ft 15 year old. Stay strong and try to relax.