637 4060 ADDRESS: 60 Mount Street Lower, Grand Canal Dock, Dublin 2 info@merrionultrasound.ie

It may surprise you to know, that our Celtic relatives in Glasgow, were the first to use ultrasound back in 1956, for clinical purposes. The first prototype was developed by an engineer, Tom Brown, and an obstetrician, Ian Donald. Believe it or not, the concept was based upon an instrument which was originally used to find flaws in ships. The team perfected its use for clinical purposes, and actually by 1960 Glasgow hospitals were using ultrasound routinely. Funnily enough, it didn’t take off in American and British hospitals until the 1970s.

Of course, since then ultrasound imaging has undergone an incredible amount of development, and by the end of the 20th century, the majority of women in the developed countries of the Western world were going for routine pregnancy scans.

Today women in Ireland and other developed countries have come to expect ultrasound pregnancy scans as being an integral part of their pregnancy journey. In a way, we may have even come to take these pregnancy scans for granted a little bit, and maybe it is only at that moment when we are considering our first early pregnancy scan, that we may really give the technology more thought.

Pregnancy scans explained

Pregnancy Scans FAQs

How many scans do you have when you are pregnant?

When are pregnancy scans offered in Ireland under the public health system? In Ireland, general best practice on our public health system offers two scans during pregnancy. Although some hospitals may have more limited resources in terms of scanner availability. However, normally, you will be offered a pregnancy scan at 12 weeks and then around 20 weeks.

The early pregnancy scan at 12 weeks is to confirm that the pregnancy is viable, in other words, that your baby is developing healthily.

This pregnancy scan confirms your baby’s heartbeat, while also checking if you are carrying multiples (twins or a larger number of babies). It also sites the pregnancy, confirming that it is your uterus. Gestational age is calculated during the early pregnancy scan. Gestational age is the age of your baby calculated from the date of your last menstrual period.

The anatomy scan, which is carried out around 20 weeks, examines your baby’s anatomy in great detail. This scan should hopefully confirm that your baby’s body is forming correctly. Sadly in some cases, abnormalities may be detected during this scan. For example problems with baby’s organs, limbs, spine, heart or brain can be detected.

When should you go for your first pregnancy scan?

If you are not considered high risk, or nothing abnormal has occurred during the first trimester of your pregnancy, then the first ultrasound is offered to you at 12 weeks in Ireland. This is called either a dating scan (as it calculates your baby’s gestational age) or an early pregnancy scan.

What months do you get ultrasounds during pregnancy?

In Ireland, women are normally offered a scan at the end of the first trimester, when they are 12 gestational weeks pregnant, so at the end of the third month. Then the second scan offered on the public health system is around 20 weeks, so about month five.

Do you usually get an ultrasound in the third trimester?

Unless there is some special reason to monitor your baby during the third trimester, you will not be offered a scan at this stage. However, women over 35 years of age may be offered a scan during the third trimester.

Of course, if your obstetrician knows that there is a particular risk or needs to monitor your baby’s development, you will be offered a scan at this time.

Another option that women in Ireland have, it to go semi-private. Some women do this for a variety of reasons. This article about this option is a useful read.

How do you know how many weeks pregnant you are?

The amount of weeks you are pregnant is actually calculated from the day of your LMP (last menstrual period). Here you can use the pregnancy due date calculator.

Is it bad to have a lot of ultrasounds during pregnancy?

Pregnancy ultrasound scans have been carried out for decades and up to now, there has been no evidence to suggest that they are harmful. The sonographer, who is the person who carries out the scans, it highly trained to ensure that the scan is safe for you and your baby.

What birth defects can be detected by an ultrasound?

Some physical birth defects can be detected at the 20-week pregnancy scan. These include spina bifida, heart defects, some types of kidney problems, cleft palate in certain cases and absent limbs.

Can you tell if a baby has Down syndrome in an ultrasound?

During the 20-week ultrasound scan, it is possible to see fluid positioned on the back of a baby’s neck. This may indicate that the baby has Down Syndrome, however further tests need to be done, to make an accurate diagnosis.

Traditionally a woman then needed to have a nuchal translucency test. However there are some risks associated with this and these days, you have the option of a non-invasive test called the Harmony Prenatal Test. The Harmony Test doesn’t put you or your baby at risk.


Nuchal Translucency

12-14 weeks


Anatomy Survey

21-22 weeks


Later Dating

10-17 weeks


Gender Scan

19 weeks onwards


Growth & Well Being

22 weeks onwards


Post Dates & Liquor

40 weeks onwards


What Our Patients Say

Gráinne Macken

This is my second visit to Merrion Fetal, I was very pleased on both occasions. Lovely quiet waiting room, appointment was on time. The 20-week scan is very detailed we enjoyed watching our baby on the large TV screen. We got some beautiful photos. The nurse was very pleasant and talked us through all the measurements and anatomy. I would highly recommend this scanning clinic.”

Áine Gibney

I had the best experience at the Merrion Fetal Health clinic for my 20-week big scan. The staff were so friendly and so nice and the lovely lady who did my ultrasound scan was amazing. She was so thoroughgoing to absolutely everything and gave me such reassurance on how my baby was growing and developing. I would recommend any Mother to be to attend here if you are looking for a comfortable, reassuring and super pleasant experience.”

Linda O'Sullivan

Highly recommend! We had an early scan due to a little scare at the start of pregnancy and then another at 12 weeks to make sure all was good again. Helen who was scanning on both days was fantastic. We felt totally relaxed and un-rushed while she took her time finding the best angle of baby to get us the clearest pictures as keepsakes all while making sure everything was perfect with baby. She reassured us throughout and I can honestly say it was the best money we ever spent getting both scans done.

Please let Helen know we are 18 weeks now and flying along Highly recommend!



About The Clinic

Merrion Fetal Health Pregnancy Scans Dublin 2

About The Consultants

Dr. Rhona Mahony

About The Team

Pregnancy scans lead sonographer at Merrion Fetal Health

Book Your Scan

Screen of Pregnancy Scan

Common Concerns

FAQs - Your Questions


GP Referral Scheme


Health Conditions


Healthy Pregnancy


Medical Studies


Patients' Information


Pregnancy Diary


Pregnancy Magazines

pregnancy health magazines

Scans & Services

18 weeks pregnancy scan facial profile Merrion Fetal Health

Susan's Trimesters

pregnancy trimesters

Videos By Consultants


Midwife sonographer facilitated

Consultant Led, Centre of Medical Excellence 


All articles on the blog and website are intended as information only. Please do not consider any of the information provided here as a substitute for medical advice. At all times seek medical advice directly with your own doctor and medical team.


This website was formerly Merrion Fetal Health. The clinic has undergone a rebrand and is now known as Merrion Ultrasound.