Decreased Fetal Movements associated with increased odds of SGA and adverse perinatal outcomes: JAMA
In low-income and middle income countries, almost 1 in 2 stillbirths occurs during labor. In high-income countries, most stillbirths occur in the antenatal period, thus potentially allowing time to mitigate this risk through lifestyle and behavior change, optimization of management of comorbidities, identification of fetuses who are small for gestational age (SGA), and education regarding the importance of monitoring fetal movements.
Movements provide 1 simple measure of fetal well-being. Perception of fetal movements that are normal for that pregnancy generally reflects an appropriately functioning central nervous system and adequate oxygenation. Fetal hypoxia, associated with acute or chronic placental dysfunction, induces activation of the peripheral chemoreflex, centralization of cardiac output to vital organs, and a reduction in fetal movements, thereby limiting energy expenditure and oxygen consumption.
Although decreased fetal movements (DFM) are associated with infants being born SGA, stillbirth, higher rates of induction of labor (IOL), emergency cesarean delivery, and adverse neonatal outcomes, the usefulness of DFM in predicting poor obstetric and perinatal outcomes is questionable, with most women who report DFM in the third trimester having outcomes without complications. Furthermore, maternal perception of fetal movements is highly subjective, and there is no universally agreed upon definition.
Currently, many international guidelines emphasize DFM as an important warning sign associated with risk of stillbirth for the fetus, and women are urged to monitor their baby's movements and alert their clinicians if concerned. However, the evidence supporting the incorporation of DFM into national guidelines and as part of a broader stillbirth reduction strategy remains limited.
Jessica M. Turner and team carried out a study to review pregnancy outcomes of women with singleton pregnancies presenting with DFM in the third trimester at a large Australian perinatal center.
This cohort study used data on all births meeting the inclusion criteria from 2009 through 2019 at Mater Mothers' Hospital in Brisbane, Australia. All singleton births without a known congenital anomaly after 28 weeks' gestation were included. Among 203 071 potential participants identified from the hospital database, 101 597 individuals met the eligibility criteria. Data analysis was performed from May through September 2020. Presentation to hospital with DFM was after 28 weeks gestation.
The primary outcome of this study was the incidence of stillbirth. Multivariate analysis was undertaken to determine the association between DFM and stillbirth, obstetric intervention, and other adverse outcomes, including being born small for gestational age (SGA) and a composite adverse perinatal outcome (at least 1 of the following: neonatal intensive care unit admission, severe acidosis [ie, umbilical artery pH <7.0 or base excess −12.0 mmol/L or less], 5-minute Apgar score <4, or stillbirth or neonatal death).
Women presenting with DFM, compared with those presenting without DFM, were younger, more likely to be nulliparous and have a previous stillbirth and less likely to have a previous cesarean delivery.
During the study period, the stillbirth rate was 2.0 per 1000 births after 28 weeks' gestation. Presenting with DFM was not associated with higher odds of stillbirth.
However, presenting with DFM was associated with higher odds of a fetus being born SGA (P = 0.01) and the composite adverse perinatal outcome (P = .02). Presenting with DFM was also associated with higher odds of planned early term birth (P < .001), induction of labor (P < .001), and emergency cesarean delivery (P < .001).
In this cohort study at a single tertiary center, researchers found that DFM was not associated with higher odds of stillbirth after 28 weeks of gestation. This finding was consistent regardless of number of presentations or gestational age at first presentation with DFM.
However, results suggest that risk of stillbirth may be increased among women with 2 or more presentations of DFM compared with women with 1 presentation. The results suggest that the association of DFM with stillbirth is likely to be mediated more by the risks associated with fetal size or perturbations in intrauterine growth rather than by DFM alone.
Maternal perception of fetal movements has long been considered a sign associated with fetal well-being. Decreased fetal movements may occur as an adaptive response to fetal hypoxia (acute or chronic) as a consequence of placental dysfunction and may be associated with fetal growth restriction or stillbirth. Consequently, DFM is perceived to be an important risk factor associated with adverse perinatal outcomes. However, maternal perception of DFM is also associated with smoking, nulliparity, fetal anomaly, and anterior placental location, with most women who present with DFM having an uncomplicated live birth.
Prevention of stillbirth is clearly achieved with the birth of a live infant, and most caregivers would feel that the trade-off between earlier birth and death is an obvious choice. However, early term birth, compared with birth at later than 39 weeks and 0 days, is associated with an increased risk of neonatal morbidity, including respiratory distress, NICU admission, neonatal hypoglycemia, and intubation.
Most importantly, researchers found a significant association between DFM and an infant being born SGA. In most instances, the etiology of infants born SGA is associated with suboptimal placental function. Indeed, there is also evidence that placentas from women with DFM are smaller with histological features associated with malperfusion. This finding supports the hypothesis that DFM may be a reflection of the fetal response to chronic hypoxia against a background of placental dysfunction and suboptimal fetal growth and fetal growth restriction.
Causative pathways that result in stillbirth are likely to be varied, reflecting the real-world experience that no single intervention, including public education campaigns emphasizing the importance of DFM, has effectively reduced stillbirth rates.
This cohort study found that presentation with DFM in the context of a fetus born SGA or presentation with DFM 2 or more times after 28 weeks' gestation were associated with higher odds of stillbirth. Presentation with DFM was also a significant risk factor associated with obstetric intervention, given that it was associated with increased rates of IOL, planned early term birth, and emergency operative birth. It is arguable whether these unintended outcomes are necessarily acceptable in all health care settings given the relatively low prevalence of stillbirth late in pregnancy. The imperative for better methods of assessing fetal well-being and women's satisfaction with planned expedited birth, as well as conducting robust health economic modeling to assess the health care costs associated with preemptive intervention, is clear.
The study's results suggest that any decision for obstetric intervention should not be based on the perceived risks of stillbirth solely associated with DFM and that management should be individualized, taking into account other potential associated maternal and fetal risk factors.
Source: Jessica M. Turner; Vicki Flenady; David Ellwood et al; JAMA Network Open. 2021;4(4):e215071.