Antenatal care is the clinical assessment of mother and fetus during pregnancy, for the purpose of obtaining the best possible outcome for the mother and child.
To achieve this objective, history and examination are complemented by screening and assessment using a combination of methods, including biochemical, haematological and ultrasound. Efforts are made to maintain maternal physical and mental wellbeing, prevent preterm delivery, to anticipate difficulties and complications at delivery, ensure the birth of a live health infant, and to assist the couple in preparation for parenting.
Antenatal care traditionally involves a number of ‘routine’ visits for assessment, to a variety of healthcare professionals, on a regular basis throughout the pregnancy. This approach to antenatal care evolved as an art in an era that preceded the current, evidence-based approach to medicine.
Early monitoring and on-going care during pregnancy is associated with more favourable birth outcomes. Compared with no antenatal surveillance, some antenatal care has a beneficial effect on affect on adverse factors such as preterm delivery, low birth weight, maternal and perinatal mortality. While some traditional practices, such as strict weight-gain restriction, the use of diuretics and the liberal use of x-rays, have been discontinued, many current clinical practices fail to stand up to scientific scrutiny. Despite this, antenatal care continues to be centred about clinical assessment, with emphasis on the regularity of visits, rather than a focus on what can be achieved at key visits during the antenatal period.
Maternity care remains a mixture of both art and science, with advantages in medical technology now allowing us to focus more on the specific requirements of the mother and fetus, with an increasing drive towards the re-appraisal of current practices.
Schedule of visits during pregnancy
The pregnant woman is seen by her general practitioner as soon as possible following the first missed period and after an initial assessment is referred on to the hospital for her first (booking) hospital visit between 8-14 weeks. Hospital referrals are increasingly instituted earlier nowadays, especially among the more health conscious older educated women, who may request screening tests for the early detection of fetal abnormality. Previously, the antenatal visits were: monthly until 32 weeks gestation, then fortnightly until 36 weeks, and weekly thereafter until delivery, resulting in up to 14 hospital visits during pregnancy. Although ‘antenatal care’ improves the outcome in terms of maternal and perinatal morbidity and mortality, there appears to be little difference in outcome between a four-visit schedule and a twelve-visit schedule. Currently the trend is towards reducing the number of attendance’s, while at the same time establishing clearly defined objectives to be achieved at each visit.
The preconception visit
The ideal first ‘antenatal’ visit is at a pre-conception clinic where health education and risk assessment can be directed towards the planned pregnancy. At that time the patient’s general health and wellbeing can be fully assessed, rubella, hepatitis and HIV status can be established, and appropriate action taken where indicated.
General advice regarding nutrition and lifestyle can be given at this time. Even a single antenatal nutritional education session during pregnancy has a significant effect on birth weight.
Advice can be given regarding the avoidance of teratogens, including those linked with excesses such as vitamin A, cigarette smoking, while ensuring an optimal dietary intake of folic acid. Following the demonstration that folate supplementation reduces the risk of a subsequent neural tube defect by 72%, in those at high risk by virtue of a previous affected pregnancy, it is recommended that at least 0.4mg folic acid is taken daily during the peri-conceptional period. Abnormal blood glucose control during the peri-conceptional period is associated with increased fetal complications and this is also an ideal time to ensure that such factors have been taken care of by sound dietary education and adjustment, and where necessary, medication.
Booking Visit (8-14 weeks)
The main purpose of the booking visit to obtain a comprehensive history, establish the gestational age and identify maternal and fetal risk factors. Baseline investigations are performed.
In most centres, women are offered a first trimester ultrasound scan for pregnancy dating, the exclusion of structural fetal abnormalities and measrement of the fetal nuchal translucency.
A management plan is then drawn up for the pregnancy, based upon the risk assessment. It is by no means inflexible and is subject to alteration at subsequent visits. If the patient has a known medical problem, e.g diabetes, the patient is referred to a dedicated combined clinic. If there is a history of genetic or familial problems, referral to a feto-maternal specialist is arranged.
If this is not your first pregnancy, it is important if there were problems in a previous pregnancy that you discuss with your doctor whether any special precautions should be taken in a future pregnancy. If you are over 35, preconception planning can be particularly helpful, as the risk of problems begins to increase after this age. It is important to stress however, that the vast majority of pregnancies in older mums will be uncomplicated.
The mid-trimester risk assessment visit (20-24weeks
The results of the tests performed at the first trimester visit and at 16 weeks are reviewed with the woman. The results of the ultrasound scan for fetal abnormality are also reviewed. In some centres, Doppler ultrasound screening of the uterine arteries is used to identify women at high risk of subsequent pre-eclampsia and intra-uterine growth restriction is offered at this stage. Further care is then planned in line with risk assessment based on the ultrasound scan and other findings.
Antenatal visits in the second half of pregnancy
Assessment of maternal health and fetal growth and well-being are pursued through these visits, which can take place in the community setting. Any incidental maternal symptoms are dealt with. This period is also important in ensuring the education of the woman regarding the rest of pregnancy and her delivery. Contraception and plans for the birth should also be discussed from an early stage especially with regards to sterilisation or other permanent contraception. This is in order to avoid unnecessary duress under emergency conditions if a Caesarean operative delivery is decided upon during labour.
Antenatal classes and the familiarisation hospital visit
During the antenatal visits informal education is provided for the pregnant woman and those supporting her through pregnancy. There are formal parenting (or parentcraft) classes organised in most units where the prospective parents are encouraged to discuss the pregnancy and delivery, and any apprehensions they may have. There are also usually sessions with others involved in their care to discuss topics like breast feeding, pain management during the delivery etc. The common objectives of these formal educational sessions include the promotion of good health habits, allaying anxiety, increasing the feelings of control and satisfaction with the pregnancy and delivery by the mother, preparation for the postnatal period, infant feeding, and subsequent contraception.
Antenatal visit with hospital team (usually around 36-38 weeks)
The primary objective of this visit is to anticipate any problems regarding the prospective delivery. Several factors are considered, including the past obstetric history, e.g. a previous Caesarean delivery for lack of progress in labour. Fetal malpresentation or malposistion is sought because these may also indicate a high likelihood of operative delivery. With the increasing number of planned home births, the final place of choice for the delivery is also decided. This is also a good time to finalise the discussions on planned contraception after delivery, especially sterilisation.
The postdates visits – Induction of labour (41 -42 weeks)
With accurate pregnancy dating, true postdate pregnancies are identified. At this visit a joint decision is taken as to whether an induction of labour is appropriate. This is current practice because of the reported association between postdates pregnancies and poor pregnancy outcome, particularly in order to prevent stillbirths due to the lack of an accurate, reliable test of fetoplacental reserve during those final few weeks of pregnancy. Induction of labour is usually performed by the 42nd week.
There are still two main methods of induction; amniotomy or surgical induction, and the medical methods using prostaglandin or oxytocin. When appropriately selected, there is a high probability of a safe uneventful vaginal delivery. If spontaneous labour does not occur by the 43rd week the likelihood of a Caesarean delivery is high, irrespective of the mode of onset labour. As the perinatal morbidity and mortality continue to rise at this stage, intervention is recommended.