Introduction

Pregnancy is a physiological process during which most women remain well and require very little medical input. However, some women develop complications with significant morbidity or mortality for their baby and, occasionally, for themselves. Providers of antenatal care must be able to distinguish between these two groups of women and arrange with them an appropriate and personalized plan of care. Such a care plan could range from the simple, with no requirement for complex investigations and care, to the more challenging, requiring substantial medical expertise to enable adequate monitoring of the mother and the fetus. The purpose of antenatal care is to support the pregnant mother through her birth experience and to distinguish the normal from the at-risk pregnancy, identifying pregnancy risk factors and stratifying care to improve the chances of a successful pregnancy culminating in a healthy outcome.

Epidemiological and observational studies have demonstrated that women who receive antenatal care have better pregnancy outcomes, with lower maternal and perinatal mortality, than those who do not. These studies have also demonstrated an association between the number of antenatal visits and pregnancy outcomes after controlling for confounding factors such as the length of gestation.

Patterns and provision of antenatal care have changed enormously in recent years in response to the opinions of consumers, providers and professional associations, and government reports. The Department of Health’s Changing Childbirth and Maternity Matters reports highlighted the need for women to be the focus of maternity care, with an emphasis on providing choice, easy access and continuity of care.^1,2 Pregnant women should be provided with care that enables them to make informed decisions about their options. Good antenatal care should focus on those practices that have been shown to be effective and have a favourable impact on maternal and fetal outcomes.

What is the purpose of antenatal care?

The aim of antenatal care is to provide support for the pregnant mother and her family, which should culminate in a safe birth and recovery. In order to achieve this, the following care objectives should be met during this period:

Antenatal risk assessment

Defining the risk of adverse pregnancy outcome posed by identifiable clinical factors can help stratify and plan antenatal care for individual women. Risk assessment has underpinned the provision of antenatal care for several decades and can inform categorization into scores that determine clinical care. Applying this concept to antenatal care, Alexander and Keirse evaluated formal antenatal risk scoring for perinatal mortality, preterm delivery, intrauterine growth restriction and low Apgar score at birth.³ They found that risk scoring performed poorly in identifying women at risk of these conditions. One reason for this observation may have been the well-known fact that screening is more effective in multiparous than nulliparous women, partly attributable to the fact that most risk markers are based on events in previous pregnancies. For risk scoring to be beneficial in antenatal care, the component factors need to have high predictive values for the adverse pregnancy outcome that they are anticipated to predict. If this is not the case, then risk scoring may result in more harm than good. Women who are labelled as being at increased risk of an adverse outcome may suffer unnecessary stress and anxiety and will be exposed to unnecessary investigations and interventions, some of which may be deleterious to the pregnancy at substantial avoidable cost to the taxpayer.

Despite the limitations of pregnancy risk scoring, assessing risk broadly can inform the care plan outlined at the beginning of antenatal care.

Assessing women for clinical risks should happen before pregnancy, throughout pregnancy, and in labour, as risk factors can change at any time during gestation, sometimes necessitating a change in care plan and intervention to mitigate those risks. One study that evaluated risk scoring during pregnancy showed that while 96% of primigravidae were considered low risk in early pregnancy, only 39% remained low risk by the end of pregnancy, 57% having developed risk factors during pregnancy or labour. Similarly, 74% of multigravidae were categorized as low risk at booking, but by the end of labour only 48% remained low risk.⁴ Since unidentified risk factors will arise during pregnancy and the majority of women will have required some form of obstetric input by the time they give birth, the value of formal risk scoring in early pregnancy has been questioned. Nevertheless, risk assessment at the beginning of pregnancy enables those women with risk factors for adverse pregnancy outcome to be identified early for appropriate referrals, so that those without identifiable risk factors can be deemed suitable for midwife/general practitioner antenatal care. For the latter group, locally agreed protocols, informed by national guidance where possible, should be established for the identification, referral and treatment of obstetric complications.

The common clinical conditions that are currently screened for during pregnancy are outlined below, in the section on the booking visit. In addition to those conditions for which supportive research evidence for screening exists, there are several pregnancy conditions that are not currently screened for routinely. It could prove reasonable to screen for some of these conditions routinely in the future if supportive research evidence, expert or consensus opinion or favourable cost–benefit considerations evolve.

Who should see women at antenatal visits, and where?

While the first antenatal contact with the pregnant woman should happen at her home or in a primary care facility such as the general practitioner (GP) surgery, and should usually be provided by the designated midwife, the formal booking clinic may be provided at the hospital, when, depending on the presence of any pregnancy risk factors, the woman may require to see an obstetrician as well. Furthermore, a hospital booking visit may enable the simultaneous conduct of ultrasound scan examinations and the performance of antenatal screening tests which may not have been feasible in the community for logistic reasons or because of gestational timing. Pregnancies not associated with any significant identifiable risk factors may then be followed up by community-based visits coordinated by the midwife or GP. Those pregnancies with risk factors that warrant obstetric input may require to be supervised by the obstetrician through regular hospital visits alternating with community-based care by the named designated midwife. Care is optimized when antenatal care is provided by a named group of professionals with whom the pregnant mother develops rapport and trust.

Antenatal interventions which are not routinely recommended

Antenatal care has traditionally involved many routine interventions with little or no research evidence of benefit. Such routine care interventions of no proven benefit include: repeated maternal weighing, breast or pelvic examination, iron or vitamin A supplementation, and routine screening for chlamydia, cytomegalovirus, hepatitis C virus, group B streptococcus, toxoplasmosis and bacterial vaginosis. The routine use of Doppler ultrasound to monitor low-risk uncomplicated pregnancies, ultrasound estimation of fetal size for suspected large-for-gestational-age unborn babies, and screening for gestational diabetes using fasting plasma glucose, random blood glucose, glucose challenge test or urinalysis are of no proven benefit. Similarly, routine fetal-movement counting, auscultation of the fetal heart, antenatal electronic cardiotocography and routine ultrasound scanning after 24 weeks have no supportive evidence of benefit in routine care of uncomplicated pregnancies.

Who should provide antenatal care?

In recent years, there has been much debate concerning the issue of which of the care professionals involved with delivering maternity services should provide antenatal care. A study carried out in Scotland in 1989 showed that obstetricians, general practitioners and midwives working together (shared care) provided 97% of antenatal care.⁵ A review of published patterns of care by the National Institute for Health and Care Excellence (NICE) recently concluded that midwife- and GP-led models of care should be offered to women with an uncomplicated pregnancy, highlighting that the routine involvement of obstetricians in the care of these women at scheduled times does not appear to improve perinatal outcomes, compared with involving obstetricians only when complications arise.⁶ Care should be provided continuously throughout the antenatal period by a small group of healthcare professionals with whom the woman feels comfortable. However, there should be clear referral paths to appropriate specialist teams for women who require additional care for pregnancy complications, since up to half of those initially categorized as ‘low risk’ will develop complications during their pregnancy, often of a minor and transient nature requiring only a small degree of medical input under a shared-care philosophy.

Over the last two decades several government working documents have recommended an integrated model of antenatal care aimed at improving continuity, minimizing duplication of effort by reducing the number of antenatal visits, and improving care quality by integrating antenatal education and clinical care in each visit.¹

Basic principles of antenatal care

The principles that should underpin antenatal care have been summarized in a guidance document published by NICE.⁶ They are as follows: