Women's perceptions and experiences of fetal macrosomia

"I felt like I had no options": Navigating an ultrasound prediction of a large baby in pregnancy

BACKGROUND

Pregnancy ultrasound is deeply embedded in maternity care worldwide, undertaken routinely and in response to clinical indicators. Though ultrasound fetal size predictions can be inaccurate, they heavily influence clinical decision-making. As a result, women with a scan prediction of a 'large' baby may be more likely to have unnecessary interventions.

AIM

This study aimed to explore the implications of an ultrasound prediction of a 'large' baby on birthing women's experiences of their pregnancies and births.

METHODS

The study was underpinned by feminist poststructural theory. Semi-structured interviews were undertaken with women who had an ultrasound prediction of a 'large' baby. Transcripts were analysed using reflexive thematic analysis, with particular attention to discourse.

FINDINGS

Dominant medicalising discourses prioritised surveillance and risk-centric care, and problematised large babies. Engagement with these produced oppressive effects on women including loss of control as they were directed towards high intervention care, and the experience of fear and guilt.

DISCUSSION

A 'large' baby prediction has a negative impact on women's experiences. Women take up dominant discourses that frame predicted large babies as a medical problem to be managed, with little tangible improvement in outcomes. They struggle with fear and guilt as they experience their pregnancies as sites of risk and are constituted as failed mothers who are responsible for their large babies.

CONCLUSION

The prediction of a 'large' baby in pregnancy has undeniably negative impacts on women. We encourage midwives to scrutinise the dominant discourses of authoritative scans and problematic large babies, becoming vectors for critical thinking and resistance.

Antenatal prediction of fetal macrosomia in pregnancies affected by maternal pre-gestational diabetes

AIMS

Higher rates of fetal macrosomia may occur in infants of women with pre-gestational diabetes compared with non-diabetic controls. Antenatal predication of fetal macrosomia remains challenging. Ultrasound over-estimated fetal weight could result in over-classification of fetuses as macrosomic with corresponding inappropriate clinical interventions. Previously we had studied a measurement - the anterior abdominal wall measurement (AAW) - to predict fetal macrosomia in fetal estimation of weight. The purpose of the study was to study whether specific third trimester ultrasound measurements with measures of glycaemic control (HbA1c) predicted macrosomia in babies born to women with pre-gestational diabetes. In particular, a new variant of this measurement (fetal anterior abdominal wall thickness (AAW), abdominal circumference (AC) ratio: AAW:AC) was investigated.

METHODS

This was a prospective cohort study in a tertiary referral maternity hospital. Serial growth scans including measurement of AAW and AC: AAW ratio was performed at 30, 33- and 36-weeks' gestation. Birth-weight data was collected, and macrosomia was defined as >90th centile based on gestational age and gender of the baby. Serial HbA1c as measured at the first antenatal visit, 14, 20- and 36-weeks' gestation were reported for this study.

RESULTS

Of the 416 pregnancies analyzed, mean maternal age was 33.3 years. One in five women were primigravida's. The mean birthweight was 3548 g (+/- 581 g), of which 142 (34%) babies were classified as macrosomic. The median gestational age at delivery was 38³ weeks (31⁴ - 40² weeks). There were 37 (9%) babies born preterm at <37 weeks' gestation. Mean AC measurements in fetuses that would be born with macrosomia compared with those with a non-macrosomic birth weight were 282 mm vs. 266 mm at 30 weeks, 318.3 mm vs. 297 mm at 33 weeks and 350 mm vs. 325 mm at 36 weeks' gestation (all p < .001). Mean AAW measurements in macrosomic fetuses compared with normal size fetuses were 3.7 mm vs. 3.3 mm at 30 weeks, 4.9 mm vs 4.3 mm at 33 weeks and 5.9 mm vs. 5.3 mm at 36 weeks' gestation (all p < .001). The mean AC: AAW was 0.01 for both normal and macrosomic fetuses at 30 weeks. There was no clinical or statistical difference in AC:AAW ratios between non-macrosomic and macrosomic infants. Binary logistic regression showed that AC at 36 weeks was most predictive of macrosomia (76.5%), followed by AAW at 30 weeks (68.5%). Using a combination of HbA1c booking, 14, 20, 36 weeks and AAW 30, 33, 36 weeks and AC 30, 33, 36 weeks predicted macrosomia in 80.9%. The ratio of AC: AAW did not act as a useful antenatal clinical predictor of macrosomia at birth.

CONCLUSIONS

Abdominal circumference at 36 weeks was the single best predictor of fetal macrosomia. A combined model of HbA1c, AC and AAW was the best antenatal predictor of macrosomia, with intriguing clinical possibilities in the possible prevention of maternal and fetal complications of macrosomia.

Determinants of the persistency of macrosomia and shoulder dystocia despite treatment of gestational diabetes mellitus

Aims

to identify potentially modifiable risk factors associated with the persistency of macrosomia and/or shoulder dystocia in infants born to women treated for gestational diabetes mellitus (GDM).

Methods

this case-control retrospective study included 113 cases complicated by macrosomia (ponderal index ≥97^th percentile) and/or shoulder dystocia, and 226 controls without these complications. Factors associated with macrosomia and/or shoulder dystocia and with failure of diabetes management were assessed by multivariable analyses.

Results

Macrosomia and/or shoulder dystocia were associated with previous delivery of a large for gestational age (LGA) infant (adjusted odds ratio, 2.34, 95% confidence interval [1.01–5.45]), three abnormal glucose values during oral glucose tolerance test (2.83 [1.19–6.72]), a higher gestational weight gain before treatment (1.08 [1.01–1.15]), and failure of diabetes management (2.68 [1.32–5.45]). A non-Euro Caucasian origin (3.08 [1.37–6.93]), previous delivery of a LGA infant (3.21 [1.31–7.87]), institution of treatment after 32 weeks of gestation (3.92 [1.86–8.25]), and insulin therapy (2.91 [1.20–7.03]) were associated with failure of diabetes management.

Conclusions

supportive care in at risk women, limitation of weight gain in early pregnancy, shortened delay between diagnosis and treatment of GDM, and intensive insulin dosage adjustments might be means to improve the neonatal prognosis of GDM.

Labor and Delivery Experiences of Mothers with Suspected Large Babies

OBJECTIVE

To characterize the prevalence of and factors associated with clinicians' prenatal suspicion of a large baby; and to determine whether communicating fetal size concerns to patients was associated with labor and delivery interventions and outcomes.

METHODS

We examined data from women without a prior cesarean who responded to Listening to Mothers III, a nationally representative survey of women who had given birth between July 2011 and June 2012 (n = 1960). We estimated the effect of having a suspected large baby (SLB) on the odds of six labor and delivery outcomes.

RESULTS

Nearly one-third (31.2%) of women were told by their maternity care providers that their babies might be getting "quite large"; however, only 9.9% delivered a baby weighing ≥4000 g (19.7% among mothers with SLBs, 5.5% without). Women with SLBs had increased adjusted odds of medically-induced labor (AOR 1.9; 95% CI 1.4-2.6), attempted self-induced labor (AOR 1.9; 95% CI 1.4-2.7), and use of epidural analgesics (AOR 2.0; 95% CI 1.4-2.9). No differences were noted for overall cesarean rates, although women with SLBs were more likely to ask for (AOR 4.6; 95% CI 2.8-7.6) and have planned (AOR 1.8; 95% CI 1.0-4.5) cesarean deliveries. These associations were not affected by adjustment for gestational age and birthweight.

CONCLUSIONS FOR PRACTICE

Only one in five US women who were told that their babies might be getting quite large actually delivered infants weighing ≥4000 g. However, the suspicion of a large baby was associated with an increase in perinatal interventions, regardless of actual fetal size.

The Suspected Macrosomic Fetus at Term: A Clinical Dilemma

Estimation of fetal weight is an important component of antenatal and intrapartum management of pregnant women. While many clinicians use ultrasound estimates of fetal weight to assess fetal growth, there are inherent challenges in both the diagnosis and management of suspected fetal macrosomia. Given the inaccuracy in estimating fetal weight, and the risks that accompany cesarean birth or induction of labor, the management of suspected fetal macrosomia requires open communication and shared decision making between the woman and her health care providers. This case study and literature review highlight the current management and recommendations for suspected fetal macrosomia.

Time to subsequent live birth according to mode of delivery in the first birth

OBJECTIVE

To estimate the rate and time to next live birth by mode of delivery.

DESIGN

Hospital-based cohort.

SETTING

Aarhus University Hospital (AUH), Denmark.

POPULATION

All pregnant women attending AUH were invited to enroll in the Aarhus Birth Cohort (ABC) study between 1989 and 2010 (n = 91,625).

METHODS

Women were followed from their first live birth until the subsequent live birth or until censoring due to study end using Cox regression models.

MAIN OUTCOME MEASURES

Rate and time to subsequent live birth according to mode of delivery.

RESULTS

46,162 index live births were identified, of which 22,462 (49%) had a subsequent live birth. Women with any type of caesarean had a 6% reduction in the rate of subsequent live birth (HR 0.94, 95% CI 0.89, 0.98), which remained unchanged in the analysis by type (emergency, HR 0.95, 95% CI 0.89, 1.02; elective, HR 0.91, 95% CI 0.85, 0.98) compared with women who had a spontaneous vaginal delivery (SVD). Operative vaginal delivery was associated with an 8% reduction in subsequent live birth rates (HR 0.92, 95% CI 0.86, 0.98) and vaginal delivery complicated by shoulder dystocia with a 19% reduction compared with SVD. Median time to next birth in days was shortest in women with a first caesarean (994 days, 95% CI 973, 1026) and longest in women with a vaginal delivery complicated by shoulder dystocia (1065 days, 95% CI 994, 1191). In women with planned pregnancies, the shortest median time to second birth was in women with breech vaginal deliveries (859 days, 95% CI 737, 1089) and the longest in women with vaginal deliveries complicated by shoulder dystocia (1193 days, 95% CI 1028, 1430).

CONCLUSION

The impact of mode of delivery on subsequent rate and time to next birth was minimal in this study. The greatest reduction was among women with assisted vaginal delivery complicated by shoulder dystocia. This study is strengthened by data on pregnancy planning as well as information on complications of pregnancy, delivery and neonatal morbidities, all of which may influence a woman's decision on subsequent birth.

Physical activity, sedentary behaviour and fetal macrosomia in uncomplicated pregnancies: a prospective cohort study

OBJECTIVE

to explore maternal energy balance, incorporating free living physical activity and sedentary behaviour, in uncomplicated pregnancies at risk of macrosomia.

METHODS

a parallel-group cross-sectional analysis was conducted in healthy pregnant women predicted to deliver infants weighing ≥ 4000 g (study group) or < 4000 g (control group). Women were recruited in a 1:1 ratio from antenatal clinics in Northern Ireland. Women wore a SenseWear(®) Body Media Pro3 physical activity armband and completed a food diary for four consecutive days in the third trimester. Physical activity was measured in Metabolic Equivalent of Tasks (METs) where 1 MET = 1 kcal per kilogram of body weight per hour. Analysis of covariance (ANCOVA) was employed using the General Linear Model to adjust for potential confounders.

FINDINGS

of the 112 women recruited, 100 complete datasets were available for analysis. There was no significant difference in energy balance between the two groups. Intensity of free living physical activity (average METs) of women predicted to deliver macrosomic infants (n = 50) was significantly lower than that of women in the control group (n = 50) (1.3 (0.2) METs (mean, standard deviation) versus 1.2 (0.2) METs; difference in means -0.1 METs (95% confidence interval: -0.19, -0.01); p = 0.021). Women predicted to deliver macrosomic infants also spent significantly more time in sedentary behaviour (≤ 1 MET) than the control group (16.1 (2.8) hours versus 13.8 (4.3) hours; 2.0 hours (0.3, 3.7), p = 0.020).

KEY CONCLUSIONS AND IMPLICATIONS FOR PRACTICE

although there was no association between predicted fetal macrosomia and energy balance, those women predicted to deliver a macrosomic infant exhibited increased sedentary behaviour and reduced physical activity in the third trimester of pregnancy. Professionals caring for women during pregnancy have an important role in promoting and supporting more active lifestyles amongst women who are predicted to deliver a macrosomic infant given the known associated risks.