Possible complications in third trimester

Possible complications in Third Trimester include:

Preterm labour This is the onset of regular painful contractions after 24 weeks and before 37 weeks gestation. The earlier the onset of labour, the worse the outcome. If you do experience regular painful contractions during this time, come in early to the hospital. Regular painful contractions could occur once every 5-10 minutes interval, and may last about 20-40 seconds in duration. Medications could be given to inhibit the labour (i.e. tocolytics), corticosteroids could be given to help reduce the possibility of breathing difficulties to the baby should the delivery occur despite the inhibition of labour, and magnesium sulphate could be given to reduce the possibility of cerebral palsy if the delivery happens before 32 weeks. 

Preterm leaking liquor This is the leakage of colourless fluid from the vagina after 24 weeks and before 37 weeks gestation. The earlier the onset, the worse the outcome. If you do experience leaking liquor, come in quickly to the hospital. Complications include preterm labour and chorioamnionitis (i.e. infection of the placenta and membranes). Corticosteroids to reduce the possibility of breathing difficulties to the baby may be given, and medications to inhibit the labour may be given if there is no chorioamnionitis.

Pre-eclampsia (PE) This is a pregnancy-induced condition that is characterised by high blood pressure (i.e. blood pressure persistently at or above 140/90 mmHg) and proteinuria (i.e. proteins in the urine) usually in the third trimester. Proteinuria usually implies involvement of the kidneys. If this occurs, further blood tests and ultrasound examination of the fetus may be required to assess the extent of this condition, and close surveillance required. Some cases of pre-eclampsia progress quickly while others progress slowly. It could progress to involve other systems including fits, bleeding in the liver, bleeding disorders, and other serious complications.

Early stages of pre-eclampsia may not have symptoms and would be missed if blood pressure and urine are not checked. However late stages of pre-eclampsia may be associated with:

• severe headaches

• vision problems, such as blurring or seeing flashing lights

• pain just below the ribs, especially on the right upper abdomen

• vomiting

• sudden swelling of the feet, ankles, face and hands

Delivery is necessary when the PE progresses significantly. The risk of PE can be assessed now at the 11-13 weeks scan, and low dose aspirin and high dose calcium supplements may be used then to reduce the risks of this from occurring. 

Gestational diabetes mellitus (GDM) This is a pregnancy-induced condition that is characterised by high blood sugar level. This is usually diagnosed from an oral glucose tolerance test at 28 weeks gestation. For this test, you need to fast overnight from 10 pm. There is a 75 g of sugar drink to be taken orally in the morning, with blood taken before taking this drink and 1 and 2 hours after the drink. If the fasting blood glucose is 5.1 or more, 1st hour post-drink is 10.0 mmol/l or more, and 2nd hour post-drink is 8.5 mmol/l or more, you have gestational diabetes mellitus.

Gestational diabetes mellitus, especially if not well controlled, increases the risks of:

• macrosomia or big baby

• shoulder dystocia (difficulties with delivery of the shoulder during labour) which may lead to birth injuries of the baby

• Caesaraean section and

• stillbirth, especially if the sugar level is not well controlled

Treatment includes: 1. Dietary modification with restriction of calories and carbohydrates. 2. Regular physical exercise 3. Need for home blood sugar monitoring. This can be accomplished by either:

a) continuous glucose monitoring (CGM) where the aim is to keep the maternal sugar level between 3.9 to 7.8 mmol/l, and the peaks after meals should be between 6.0 to 7.8 mmol/l, or

b) blood sugar profile (BSP) with intermittent pricks of the finger to do hypocount readings of at least 7 times in 1 week. 4. If BSP pre-meals persistently >= 5.3 mmol/l (95 mg/dl), 1st hour post-meals persistently >=7.8 mmol/l (140 mg/dl) and 2nd hour post-meals persistently >= 6.7 mmol/l (best 5.9-6.4 mmol/l or <120 mg/dl), or HbA1c >6.0 - 6.5%, may require oral medications like metformin. 5. If BSP still poor despite metformin, may require insulin injections. This occurs in about 20-30% of patients who were initially started with metformin. 6. Timing of delivery - usually between 38-40 weeks.

Fetal growth restriction (FGR) or the older term was intrauterine growth restriction (IUGR) This is diagnosed when the estimated fetal weight is smaller than usual, or if there is a reduction in the growth velocity of the estimated fetal weight. If this is due to poor placental function, it is often accompanied by adverse blood flow changes in the fetus and reduced amniotic fluid. Premature delivery may be indicated if it is judged that early delivery is safer than keeping the fetus within the uterus.

Macrosomia This is diagnosed when the estimated fetal weight is larger than usual. A potentially more difficult vaginal delivery is anticipated when the fetus is too large. This could result in Caesarean section, forceps / vacuum delivery, difficult vaginal delivery sometimes with obstruction of the shoulder after the head is delivered. Inherently the estimated fetal weight is accurate within a 15% margin of error. For a large fetus measuring 4 kg, this could mean that the actual fetal weight ranges from 3400 g to 4600 g. If the measurements are done serially, the margin of error may be reduced.