About Your Second Trimester (14-26 weeks)
Some things to consider in your second trimester:
Finding Out Your Baby’s Gender
Whilst many parents-to-be choose to wait until baby is born, others may wish to find out the gender of their unborn baby. This can be seen from about 16 weeks based on a transabdominal scan with an accuracy of over 90%. Non Invasive Prenatal Testing (NIPT) is much more accurate.
Growth Scans (14-24 weeks)
Traditional antenatal care in your second trimester is based on measuring the bump (symphysis – fundal height) and detects about 30% of babies who are not growing properly. Plotting the growth measurements on a customised chart (GROW) by trained midwives in a highly structured way (following the GAP Programme) will improve this to about 50%. So whilst this is important, you’re right to spot that about half of the babies who are growth restricted and at increased risk of stillbirth will still be missed. Having regular growth ultrasound scans can help to address this.
Growth scans will assess fetal size and other aspects of fetal well-being such as the amniotic fluid volume. Regular scheduled scans also allow the chance to follow the rate of growth (growth velocity) as this is more important than just measuring size alone. A small baby that is growing normally should be healthy whereas a big baby whose growth has slowed may be in difficulties and at risk. Babies who are significantly compromised or at risk of stillbirth may need close surveillance and possibly early delivery.
Anomaly Scan (20 weeks) – part of routine NHS care
This transbdominal scan can detect:
- about 70% of major structural abnormalities
- about 99% of babies with conditions like spina bifida
- about 50% of babies with major heart defects
- a low lying placenta (placenta praevia)
- a blood vessel which overlies the placenta (vasa praevia, which is rare but can cause lethal bleeding in labour) – it’s really important to know that your NHS Anomaly Scan will not screen for vasa praevia
Screening for Pre-Eclampsia (20-24 weeks)
Pre-eclampsia is when a pregnant woman develops high blood pressure; this is often associated with swelling especially in the ankles and protein in the urine. There is no cure but it can be managed and sometimes requires early delivery. It can have very serious implications such as maternal fits, stroke and liver and kidney damage in the woman and growth restriction and stillbirth in the baby.
Routine antenatal care includes regular scheduled checks on blood pressure and urine testing. Since the condition is more common in first pregnancies, the schedule is more regular, but it can occur earlier than expected or in between routine checks and so even more frequent checks may sometimes be wise. The condition also affects placental blood flow and so regular ultrasound assessment of fetal well-being may also be recommended. An ultrasound scan at 20-24 weeks (Uterine Artery Doppler) can identify if you’re at increased risk of pre-eclampsia, poor placental function and growth restriction so that you can consider more frequent checks for you and baby.
Cervical Incompetence & Preterm Birth
Preterm birth is a major cause of death and disability in newborn babies, affecting 6-8% of pregnancies. Some pregnancies are recognised as being at increased risk such as those who have had a previous very preterm birth, cervical surgery (e.g. cervical cone biopsy or more than one LLETZ procedure), suspected cervical incompetence or multiple pregnancies. In many cases, sadly there are no warning signs, but there are tests and scans that can help to identify if you’re at increased risk.
A transvaginal ultrasound scan (Cervical Incompetence Scan) at 16 weeks can assess the cervix to identify pregnancies at increased risk of preterm delivery.
A Fetal Fibronectin Test, between 22 to 35 weeks, can predict preterm birth based on a vaginal swab. The results are available in about 20 minutes. A negative result means that there is over a 99% reassurance that you won’t go into labour in the next two weeks. This is particularly useful if you’re going on international holidays or if your partner is travelling or away during the pregnancy. A positive result indicates a high risk of early delivery.
An abnormal Cervical Incompetence Scan or a positive Fetal Fibronectin Test allows various interventions to be discussed such as a cervical stitch, drugs to relax the uterus and steroids to reduce breathing difficulties in the baby if it is born early.
Vaccinations for Flu & Whooping Cough
- Flu vaccination is offered to pregnant women to reduce the risk of developing a serious infection which may result in early delivery or termination.
- Whooping cough can cause serious infections in newborn and young babies before they’re old enough to be vaccinated. All pregnant women are advised to consider being vaccinated any time from 16 weeks.