The Third Trimester

From Week 27 Until Delivery

Gestational Diabetes Screening

Women will be checked for gestational diabetes between 24 and 28 weeks, if this was not completed in the second trimester.

GESTATIONAL HYPERTENSION OR PRE-ECLAMPSIA

Pre-eclampsia is a condition unique to pregnancy where a woman’s blood pressure rises in late pregnancy, and protein is lost in the urine. This can lead to swelling (edema) of the hands, feet, and face, and rapid weight gain. An important part of prenatal care in the third trimester is monitoring for pre-ecclampsia. Blood pressure is checked at every visit and the urine may also be checked for protein. In women with elevated blood pressure, blood tests might also be ordered.

Symptoms of concern that women should report include severe headaches, blurry vision or spots before their eyes, and severe pain in the upper abdomen, especially on the right side.

Pre-eclampsia can be very hazardous for both the mother and baby. In severe cases, women can become critically ill and develop seizures (eclampsia). The placenta can malfunction, leading to impaired growth and fluid around the baby, and even death of the baby in utero (stillbirth).

Treatments include medications to lower blood pressure, and, in severe cases, medications to prevent seizures. Admission to the hospital may be required. Definitive treatment involves delivery of the baby, but whether or not this is advised depends on how close to term the pregnancy is. The disease can actually worsen after delivery before it starts to improve and, in rare cases, pre-eclampsia can occur for the first time after the birth.

Planned C-Section

If a C-section is the planned mode of delivery, booking paperwork will be completed at around 32-33 weeks. Common reasons for a planned C-section include previous C-section, placenta previa (placental location will usually be confirmed at 32 weeks), twins, and breech presentations. If the reason is a breech baby, the booking will be done after 35-36 weeks, when the breech presentation is confirmed to persist.

While OBs encourage healthy women to deliver vaginally, maternal choice C-section (without medical need) is supported after informed consent.

BREECH PRESENTATION

Babies usually assume a head-first position by the end of the third trimester. If the baby is breech (bum first) at 34-36 weeks, there is a chance that the baby will not turn spontaneously. Breech deliveries are higher risk for the baby. If the baby remains in a breech position at 34-36 weeks, the OB will discuss the options of external cephalic version (ECV), cesarean delivery, and vaginal breech delivery.

Our OBs support vaginal breech delivery when women meet certain criteria, are motivated to try, have been fully informed of the risks involved, and agree to the recommended hospital protocols.

Group B Strep

Group B strep (GBS) is a type of bacteria that can be found in the vagina or rectum of about 30% of pregnant women in this region. GBS does not cause symptoms or illness in the mother. However, babies can acquire GBS in their nose or mouth, as they pass through the birth canal in a vaginal delivery. Because their immune system is immature, this can lead to serious life-threatening illnesses such as infection of the blood (sepsis), lungs (pneumonia) or nervous system (meningitis). Premature newborns are particularly vulnerable.

Women are checked to see if they carry GBS by obtaining a vaginal/anal swab between 35 and 37 weeks of pregnancy, and GBS positive women are given IV antibiotics in labour, as these will cross the placenta and provide protection for the baby.

Women who have had GBS in their urine at any point in the pregnancy are considered to have a heavy growth of GBS, and will receive the IV antibiotics in labour; doing the swab is therefore not necessary.

If a swab has not been done, women will receive IV antibiotics in labour if there are risk factors, such as prematurity, a previously affected baby, or if the waters have been broken for many hours (prolonged rupture of the membranes).

FeTAL MOVEMENT COUNTS

In the third trimester, women generally feel their baby move quite regularly. When women perceive a decrease in fetal movements, a formal fetal movement count should be done. Women with high-risk pregnancies may be asked to doroutine daily fetal movement counts.

Preparing for the Birth

For the first pregnancy in particular, prenatal classes are a great idea. They cover the basics of pregnancy, the delivery, breastfeeding and infant care. They typically start at about 30 weeks, but registering early is important, as they get quite busy.

Decisions regarding cord blood banking are made. In the public option, the consent needs to be completed (paper form or online). For private banking, this needs to be arranged directly with the company and a kit will be provided to bring to the hospital at the time of the birth.

Women wishing doula support in labour will typically arrange this in the third trimester.

Typically, at the visit following the GBS swab, the OB will provide instructions about what to do when labour begins. While guides are provided on the website, the OB will provide specific instructions pertaining to the woman’s individual situation.

Women who have chosen to prepare a birth plan can present it to their OB at this time. Writing a birth plan can be a useful exercise for some prospective parents, but they are not necessary. If done, they should be kept flexible, as birth is very unpredictable and having a rigid set of expectations can lead to disappointment.

PostDates Pregnancy

Early term is reached at 37 weeks, and full term is reached at the due date (40 weeks). Pregnancies that proceed beyond the due date are considered overdue or postdates.

OBs may recommend a cervical examination between 38 weeks and 41 weeks, to check on the status of the cervix and see how ready it is for labour. A ‘membrane sweep’ may be offered. This is a procedure where the examining fingers gently stretch the cervix (if it admits at least a fingertip) and separate it from the membranes. This releases natural compounds called cytokines which can trigger the onset of labour. The procedure can be painful, and is not guaranteed to do anything, but it can sometimes be quite effective, obviating the need for a formal induction of labour for postdates.

In women under age 40 with low-risk pregnancies, the protocol for postdates pregnancies is for fetal monitoring (limited ultrasound for fluid assessment and cord dopplers + non-stress test or NST) to take place at 10 days past the due date (41w0d), because the risk of stillbirth starts to increase at this point. Induction of labour will typically be recommended when pregnancies are 10 days overdue (41w3d). Women wishing to wait longer will have fetal monitoring every 2 days after 41w3d.

Women over 40 have a higher risk of stillbirth and induction of labour is recommended one week before the due date (39w0d).