Clinical Practice Guidelines Antenatal Care — Module II
Fetal growth and wellbeing
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- Perinatal deaths associated with intrauterine growth restriction in Australia
- Risk factors for intrauterine growth restriction
- Decreased fetal movement
- Reporting of decreased fetal movement
- Discussing fetal movement
- Discussing fetal heart rate assessment
- Practice summary: Fetal growth and wellbeing
6.36.4Fetal growth and wellbeingAntenatal visits provide an opportunity to assess fetal growth, auscultate the fetal heart (although this cannot predict pregnancy outcomes) and encourage women to be aware of the normal pattern of fetal movements for their baby. Fetal growthDuring pregnancy, the baby passes through various stages of growth and development. Monitoring growth aims to identify small- and large-for-gestational age babies, both of whom are at increased risk of associated morbidity and mortality. Current practice in Australia for monitoring growth is assessment by abdominal palpation, symphysis–fundal height measurement, or both. Perinatal deaths associated with intrauterine growth restriction in AustraliaA baby whose estimated weight is below the 10th percentile for its gestational age is considered to be affected by intrauterine growth restriction (Li et al 2012). In Australia in 2010, intrauterine growth restriction was the cause of 6.8% of perinatal deaths among singleton babies (Li et al 2012). Perinatal deaths associated with intrauterine growth restriction among singleton babies were most common at 32–36 weeks gestation (11.3%). Among all perinatal deaths, intrauterine growth restriction was more common among mothers aged less than 20 years (8%) and more than 40 years (9.4%). Risk factors for intrauterine growth restrictionIntrauterine growth restriction has been associated with pregnancy related hypertension, pre-existing diabetes, autoimmune disease, maternal heart disease, toxic exposure to smoking, alcohol or drugs, malnutrition, living at high altitudes, living in developing countries, low socioeconomic status, ethnicity, family or prior history of intrauterine growth restriction, extremes of maternal age, fetal genetic disease, fetal malformations, multiple gestation, placental anomalies, fetal infection and maternal malaria (Sabogal & Weiner 2009). Summary of the evidenceThe evidence on methods of growth assessment is limited: an observational study found that abdominal palpation had limited value as a screening tool for intrauterine growth restriction in low-risk pregnancies (n=6,318) (Bais et al 2004); two Cochrane reviews (based on the same study) found no difference in detection of intrauterine growth restriction between repeated symphysis–fundal height measurement and abdominal palpation (Neilson 2009; Robert Peter et al 2012); and detection of intrauterine growth restriction has been shown to be improved by plotting fundal height measurements on fetal growth charts customised for maternal height, weight, parity and ethnic group in an observational study (Roex et al 2012). Although current evidence does not conclusively support either method for detecting low or high birth weight babies, monitoring growth is important (Robert Peter et al 2012). Monitoring of fetal growth in women whose pre-pregnancy BMI is high (HAPO 2010) or in the underweight category (Dawes & Grudzinskas 1991; Panaretto et al 2006) is of particular importance. Referral for specialist advice is required when there is a discrepancy of 3 cm between observed and expected symphysis-fundal height measurements. Consensus-based recommendation i Offer women assessment of fetal growth (abdominal palpation and/or symphysis-fundal height measurement) at each antenatal visit to detect small- or large-for-gestational-age infants. Practice point o Further investigations, such as ultrasound, are a consideration when there is any doubt about fetal growth. This includes ultrasound for women with a BMI ≥30 kg/m2 as clinical assessments of fetal growth have been shown to be less reliable in this group. Studies into estimating birth weight before labour have found that: sensitivity and specificity were similar using ultrasound (12.6%; 92.1%), abdominal palpation (11.8%; 99.6%) or maternal estimate (6.3%; 98.0%) (n=246) (Ashrafganjooei et al 2010); abdominal palpation was within 10% of actual birth weight in 65% of babies, with lower accuracy for low birth weight (n=320) (Belete & Gaym 2008); abdominal palpation and ultrasound had similar sensitivity and specificity for normal and low birth weights but ultrasound had higher specificity for high birth weight (n=174) (Khani et al 2011); and ultrasound was more accurate in predicting low or high birth weight than abdominal palpation (n=262) (Peregrine et al 2007).
Fetal movementsMaternal perception of fetal movement (defined as any discrete kick, flutter, swish or roll) (Neldam 1983) is one of the first indications of fetal life. Most pregnant women become aware of fetal activity between 18 and 20 weeks of gestation (RCOG 2011). Due to a lack of epidemiological studies on fetal activity patterns and maternal perception of fetal activity in normal pregnancies, it is not clear what constitutes a ‘normal’ pattern of fetal movement (RCOG 2011). There is considerable variation in fetal movements and estimates cover a wide range (eg from 4–100 movements per hour) (Mangesi & Hofmeyr 2007). Decreased fetal movementA significant reduction in fetal movement may be associated with poor perinatal outcomes (RCOG 2011). Women’s perception of decreased fetal movement is reduced with an anterior placenta, cigarette smoking and maternal obesity (Tuffnell et al 1991). Incidence of decreased fetal movement: maternal reporting of decreased fetal movement occurs in 5–15% of pregnancies in the third trimester (Froen 2004; Heazell et al 2008; Flenady et al 2009). Risks of decreased fetal movement: decreased fetal movement indicates that even women with low-risk pregnancies may be at greater risk of adverse outcomes, including intrauterine growth restriction, fetal death and preterm birth (ANZSA 2010). However, the absence of perceived fetal movements does not necessarily indicate fetal compromise or death (Mangesi & Hofmeyr 2007). Due to the lack of high quality evidence, there is considerable variation in the information provided to women about decreased fetal movements (Heazell et al 2008; Flenady et al 2009; Unterscheider et al 2010). Summary of the evidenceFetal movement assessment is widely used to monitor fetal wellbeing (Froen et al 2008; O'Sullivan et al 2009) and is most commonly undertaken through subjective maternal perception. Fetal movement counting is a more formal method to quantify fetal movements (Mangesi & Hofmeyr 2007). Maternal perception rather than formal fetal movement counting is recommended in Australia (ANZSA 2010) and in the United Kingdom (NICE 2008b; RCOG 2011). Fetal movement countingA systematic review (n=71,730) (Mangesi & Hofmeyr 2007) found insufficient evidence to recommend for or against fetal movement counting to prevent adverse perinatal outcomes, as the included trials did not compare the effects on perinatal outcome of fetal movement counting with no fetal movement counting. A subsequent systematic review of single studies (Heazell & Froen 2008) concluded that at present, there is no evidence that any absolute definition of reduced fetal movements is more valuable than maternal perception of reduced fetal movements in detecting intrauterine fetal death or fetal compromise. However, a recent RCT (n=1,076) found that maternal ability to detect clinically important changes in fetal activity seemed to be improved by fetal movement counting, with increased detection of intrauterine growth restriction and improved perinatal outcomes but not perinatal mortality (Saastad et al 2011). Reporting of decreased fetal movementGuidelines from Australia (ANZSA 2010) and the United Kingdom (RCOG 2011) recommend that women contact their health professional or maternity unit if they are concerned about a reduction in or cessation of fetal movements after 28 weeks of gestation. A recent systematic review (Hofmeyr & Novikova 2012) concluded that there are insufficient data from randomised trials to guide practice regarding the management of decreased fetal movement. Current management strategies include early birth, expectant management with close surveillance of the baby, cardiotocography, ultrasound examination and fetal arousal tests (either cardiotocography or clinical observation where electronic fetal assessment methods are not available) to assess the baby’s wellbeing (Hofmeyr & Novikova 2012). Consensus-based recommendation ii Advise women to be aware of the normal pattern of movement for their baby and to contact their health care professional promptly if they have any concerns about decreased or absent movements. Discussing fetal movementInformation given to women should include that: most women are aware of fetal movements by 20 weeks of gestation, and although fetal movements tend to plateau at 32 weeks of gestation, there is generally no reduction in the frequency of fetal movements in the late third trimester (RCOG 2011); patterns of movement change as the baby develops, and wake/sleep cycles and other factors (eg maternal weight and position of the placenta) may modify the mother’s perception of movements (ANZSA 2010); most women (approximately 70%) who perceive a single episode of decreased fetal movements will have a normal outcome to their pregnancy (RCOG 2011); and if a woman does report decreased fetal movement, a range of tests can be undertaken to assess the baby’s wellbeing.
Summary of the evidenceAuscultationRoutine auscultation of the fetal heart rate is not recommended in the United Kingdom (NICE 2008a). Although successful detection of a fetal heart confirms that the baby is alive, it does not guarantee that the pregnancy will continue without complications (Rowland et al 2011) and is unlikely to provide detailed information on the fetal heart rate such as decelerations or variability (NICE 2008a). The sensitivity of Doppler auscultation in detecting the fetal heart is 80% at 12+1 weeks gestation and 90% after 13 weeks (Rowland et al 2011). Attempts to auscultate the fetal heart before this time may be unsuccessful, and lead to maternal anxiety and additional investigations (eg ultrasound) in pregnancies that are actually uncomplicated (Rowland et al 2011). It is unlikely that the fetal heart will be audible before 28 weeks if a Pinard stethoscope is used (Wickham 2002) Although there is no evidence on the psychological benefits of auscultation for the mother, it may be enjoyable, reduce anxiety and increase mother–baby attachment. Consensus-based recommendation iii If auscultation of the fetal heart rate is performed, a Doppler may be used from 12 weeks and a Pinard stethoscope from 28 weeks. CardiotocographyElectronic fetal heart rate monitoring is not recommended as a routine part of antenatal care in the United Kingdom (NICE 2008a) or Canada (Liston et al 2007). A Cochrane review found no evidence on the use of cardiotocography in women at low risk of complications (Grivell et al 2010). Anxiety levels in women who undergo routine cardiotocography are increased. This reaction seems to be influenced by the perception of fetal movement during the examination and is more evident in women whose pregnancies are affected by obstetric complications (Mancuso et al 2008).
Routine use of antenatal electronic fetal heart rate monitoring (cardiotocography) for fetal assessment in women with an uncomplicated pregnancy is not supported by evidence. Practice summary: Fetal growth and wellbeing
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