Antenatal care

Published on 09/03/2015 by admin

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Chapter 26 Antenatal care

Prepregnancy care

Ideally, all couples should seek prepregnancy care. Most couples are not reviewed until after the critical fetal developmental period.

Aims of counselling before conception

• Advise the woman and her partner on general healthcare (e.g. on nutrition/diet/folate, smoking, alcohol and drugs).

• As the oral contraceptive pill may deplete red cell folate, use alternative contraception for 1 month while commencing folic acid.

• Carry out general screening, including rubella and varicella serology, and immunise when required; cervical cytology; blood pressure.

• Assess and advise on the effects of existing disease and its management on the pregnancy, and the effects of pregnancy on the disease. Treat preexisting diseases to minimise the problems that may arise in pregnancy.

• Assess and advise on the problems that may recur from previous pregnancies and deliveries.

• Provide genetic counselling with full genetic history, especially in high-risk racial groups.

• Preconception care often requires a team of obstetricians, physicians, geneticists, dietitians, and specialised educators such as diabetic educators.

Antenatal care

Antenatal clinics act as a screening tool to identify and then manage problems that arise during the pregnancy. As this is also often the first time healthy women are assessed, they may provide information for long-term healthcare.

Aims of antenatal care

• Screen and manage/prevent maternal problems.

• Screen and manage/prevent fetal problems.

• Provide antenatal education regarding general health, nutrition and childbirth.

Examination

• weight, height

• blood pressure, urinalysis

• general: teeth/gums, thyroid, breast, chest, heart, varicose veins

• abdomen: scars, fundal height, masses, pain

• pelvic: cervical cytology if indicated; vaginal examination

Investigations

First visit

• full blood examination

• ABO blood type, Rhesus blood group and antibodies (the antibody screen should be performed at the beginning of every pregnancy)

• rubella immunity (antibody titres may decline, so check at the start of each pregnancy)

• syphilis serology using specific Treponema assay (e.g. T. pallidum haemaglutination assay (TPHA))

• hepatitis B serology

• urine for culture and sensitivity

• hepatitis C and human immunodeficiency virus (HIV) serology, offered after appropriate counselling

• cervical cytology if no normal smear within the previous 18 months

Other tests considered but not mandatory include:

• testing for vitamin D deficiency in dark-skinned or veiled women

• screening for haemoglobinopathies (especially if mean corpuscular volume (MCV) or mean corpuscular haemoglobin concentration (MCHC) are abnormal)

• varicella serology

• cytomegalovirus (CMV)/toxoplasma serology: recommended only in at-risk women and ideally as prepregnancy test

Discussion of antenatal screening

Antenatal screening for Down syndrome and other fetal aneuploidy should be discussed (see Ch 27).

Obstetric ultrasound scan at 18–20 weeks gestation

All women should be offered fetal morphology assessment prior to 20 weeks gestation.

Haemoglobin, platelet count, Rhesus antibody status

• should be reviewed at 28 weeks gestation

• if anaemic, then iron deficiency investigated

Gestational diabetes

Screening is recommended.

Group B streptococcus disease (GBS)

This is the leading cause of neonatal sepsis, which if left untreated would affect 1 in 200 newborns, with intrapartum chemoprophylaxis significantly decreasing infection rates. The decision for prophylaxis comes from either screening via low vagina/anorectal swab at 35–37 weeks gestation or treating via clinical risk factor analysis.

Continuing antenatal visits

• routine antenatal visits every 4 weeks to 28 weeks gestation, then every 2 weeks to 36 weeks gestation, then every week until delivery

• at each visit, assessment of:

• history of events since previous visit, fetal movements, blood pressure, review of risk factors

• fundal height, clinical amniotic fluid assessment, fetal heart sounds, and (in the third trimester) fetal lie and presentation

• discussion of anti-D prophylaxis at 28 and 34 weeks gestation, and at any time of blood loss in a Rhesus-negative woman

Indications for ultrasound scan in antenatal care

• First trimester: vaginal bleeding, abdominal pain, hyperemesis gravidarum, before procedures (e.g. amniocentesis, chorionic villus sampling or cervical suture). Down syndrome screening and definitive diagnosis of multiple pregnancies is offered early in the second trimester.

• Second trimester: at 18–20 weeks to confirm dates, assess fetal morphology and exclude multiple pregnancies; to assess complications of pregnancy, including antepartum haemorrhage, threatened premature labour and preterm prelabour rupture of membranes.

• Third trimester: fundal height small or large for gestation, previous intrauterine growth restriction, multiple pregnancies, antepartum haemorrhage, malpresentation, maternal medical conditions such as diabetes, renal disease, pre-eclampsia. Late pregnancy tests of fetal wellbeing for assessment of the fetoplacental function may be appropriate.

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