Objective
The aims of this study were evaluation of the association of reduced fetal movements (RFM) and small-for-gestational-age (SGA) birth at term and to explore if fetal and maternal outcomes are different with single vs repeated episodes of RFM and normal fetal assessment test results.
Study Design
This was a retrospective cohort study of all singleton pregnancies referred for RFMs at a tertiary fetal medicine unit from January 2008 through September 2014. Ultrasound and Doppler indices were obtained from a computerized ultrasound database and pregnancy outcome was collected from hospital records.
Results
Of the 21,944 women with a singleton pregnancy booked for maternity care during the study period, 1234 women (5.62%) reported RFMs >36+0 weeks. Of these, 1029 women (83.4%) reported a single episode of RFM and 205 (16.6%) had ≥2 presentations for RFM. Women with repeated RFMs had a significantly higher mean uterine artery pulsatility index in the second trimester. The prevalence of SGA baby at birth in women presenting with a single episode as compared to repeated episodes of RFM was 9.8% and 44.2%, respectively (odds ratio, 7.3; 95% confidence interval, 5.1–10.4; P < .05).
Conclusion
Repeated episodes of RFMs at term are more likely to occur in women with high second-trimester uterine artery Doppler resistance indices and are strongly associated with the birth of SGA infants. Women presenting with repeated episodes of RFM should be treated as being at high risk of placental dysfunction irrespective of the results of prenatal ultrasound and Doppler assessment.
Reduced fetal movements (RFM) are an important and frequently seen problem in maternity care, with 6-15% of women reporting at least 1 episode of RFM during the third trimester of pregnancy. RFM, defined as a subjective perception of significantly reduced or absent fetal activity, is emerging as an important clinical marker to identify women with high risk of stillbirth and fetal growth restriction due to placental dysfunction. In fact, the majority of stillbirths seem to be preceded by a period of RFM for 3-4 days and 55% of women who have had stillbirth experience RFMs before fetal demise. Recently it has been shown that women with RFMs have abnormal placental morphology and function, suggesting a potential association between placental insufficiency and presence of RFMs. Several recent studies have reported that uterine artery (UtA) Doppler indices and pregnancy-associated plasma protein (PAPP)-A, both related to poor trophoblast development, are associated with placenta-related complications such as preeclampsia, intrauterine growth restriction, and stillbirth.
Assessment of women presenting with RFM is directed at identification of small fetuses due to placental dysfunction. Although women found to have normally grown fetuses are reassured, some of them will present with another episode of RFM despite normal results of tests of fetal well-being. The aims of this study were evaluation of the association of RFM and small-for-gestational-age (SGA) fetuses at term and to explore if the fetal and maternal outcomes are different in the cohort of women with repeated RFM and normal fetal assessment test results.
Materials and Methods
This was a retrospective cohort study of all singleton pregnancies referred for RFMs at a tertiary fetal medicine unit from January 2008 through September 2014. Part of this population, from 2008 through 2012, was reported in a previous study. Pregnancies were dated by measurements of crown-rump length in the first trimester according to the national guidelines. PAPP-A levels were measured at the time of routine 11-14 weeks’ first-trimester combined screening test for Down syndrome. UtA Doppler indices were measured at the time of routine anomaly scan between 19-23 weeks of gestation in nulliparous and high-risk parous women. UtA Doppler assessment was performed transabdominally as previous described. Pulsatility index (PI) of the left and the right UtA was averaged to compute mean PI and plotted against a published reference range. Women with UtA PI >90th centile at the second-trimester scan were offered growth scans at 28 and 36 weeks of gestation, counseled regarding the increased risk of preeclampsia, and asked to self-refer if they developed characteristic symptoms of the disorder. Low-dose aspirin for prevention of preeclampsia was not used routinely during the study period. Seven experienced operators with >5 years’ experience in obstetric ultrasound and Doppler assessment performed all the scans. Ultrasound assessments were performed using GE Voluson E8 (GE Healthcare, Zipf, Austria). Maternal characteristics, including age, body mass index (BMI), and ethnic origin, were recorded during the first visit and the outcomes of pregnancies were collected.
Women presenting 1 or >1 episode of RFM during the study period were evaluated in the fetal day assessment unit. Those presenting with RFM ≥28 weeks underwent assessment of fetal well-being. The primary reason for the fetal assessment was the first or repeated episode of RFM. Electronic fetal heart rate (computerized cardiotocography) monitoring was performed until the Dawes-Redman criteria were met and an ultrasound fetal evaluation of biometry, liquor volume, and fetal Doppler were performed. No follow-up was arranged if computerized cardiotocography, ultrasound, and Doppler assessment were noted as normal. Delivery or follow-up scans were arranged as appropriate for any suboptimal assessments. SGA was defined as birthweight (BW) <10th centile for gestational age. Pregnancies with major structural abnormalities, aneuploidy, or multiple gestations were excluded.
Statistical analysis
Data distribution was assessed according to the Kolmogorov-Smirnov test of normality. Data were expressed as mean (SD), or median and interquartile range. Categorical variables were described as number (%). The correlation between continuous variables was assessed by Pearson coefficient or by Spearman rho. Pearson χ 2 test was used to analyze categorical variables. Independent t test and Mann-Whitney test were used to compare continuous variables as appropriate. UtA mean PI centiles and BW centiles and z-scores were calculated from the appropriate reference ranges. UtA mean PI was corrected for gestational age and multiple of medians were calculated on the reference ranges from the published centiles. Logistic regression analysis was used to assess the association of maternal characteristics, first- and second-trimester markers, and fetal outcomes for women with 1 or >1 episode of RFM and SGA; P < .05 was considered statistically significant. All P values were 2-tailed. Statistical analysis was performed using statistical software (SPSS 20.0; SPSS Inc, Chicago, IL).
Results
The demographic and pregnancy characteristics of the cohorts presenting with 1 or >1 episode of RFM and SGA babies >36 weeks of gestation are presented in Tables 1 and 2 . During the study period, 21,944 women with singleton pregnancies were booked for routine antenatal care in the department. There were 1234 women (5.6%) who reported RFMs at term: 1029 women with a single episode of RFM and 205 with repeated (≥2) episodes of RFM ( Table 1 ). Of 1234 patients with RFMs, 473 (38.3%) had induction of labor (IOL) at term. The indications of delivery are presented in Table 3 .
| Demographic | Total (n = 1234) | 1 RFM episode (n = 1029) | Repeated RFM (n = 205) | Significance between 1 and repeated RFMs |
|---|---|---|---|---|
| Maternal age | 29.9 (±5.5) | 30.0 (±5.5) | 29.4 (±5.7) | .171 |
| BMI | 25.31 (±5.3) | 25.2 (±5.2) | 25.8 (±5.8) | .147 |
| Caucasian | 786 (63.9%) | 670 (65.9%) | 116 (57.7%) | < .05 |
| Afro-Caribbean | 189 (15.3%) | 156 (15.4%) | 33 (16.4%) | .704 |
| Asian | 296 (23.9%) | 240 (23.6%) | 56 (27.9%) | .201 |
| Other | 11 (0.9%) | 8 (0.8%) | 3 (1.5%) | .334 |
| Nulliparous | 704 (57.0%) | 582 (57.0%) | 122 (59.5%) | .116 |
| First- and second-trimester variables | ||||
| PAPP-A MoM | 1.18 (0.7–1.42) | 1.15 (0.69–1.41) | 1.32 (0.70–1.46) | .583 |
| BhCG MoM | 1.20 (0.65–1.47) | 1.22 (0.65–1.47) | 1.10 (0.64–1.37) | .131 |
| Mean UtA PI | 0.89 (±0.42) | 0.87 (±0.26) | 0.98 (±0.27) | < .05 |
| Scan assessment at RFM presentation | ||||
| Gestational age first episode of RFM | 38.5 (36.6–40.2) | 39.0 (37.3–40.2) | 36.3 (33.5–38.6) | < .05 |
| EFW first episode of RFM | 3240 (±640) | 3374 (±480) | 2567 (±874) | < .05 |
| EFW centile first episode of RFM | 55.76 (34.5–75.4) | 57.5 (37.0–76.3) | 40.1 (19.8–65.8) | < .05 |
| Suspected SGA first episode of RFM | 37 (2.9%) | 21 (2.0%) | 16 (7.8%) | < .05 |
| Outcome at birth | ||||
| Gestational age delivery | 40.3 (39.3–41.2) | 40.4 (39.4–41.2) | 40.1 (39.1–41.1) | .479 |
| Birthweight | 3367 (±508) | 3418 (±465) | 3113 (±622) | < .05 |
| Birthweight centile | 39.7 (19.0–67.0) | 41.5 (21.4–70.6) | 15.9 (3.9–53.9) | < .05 |
| SGA | 184 (15.6%) | 96 (9.8%) | 88 (44.2%) | < .05 |
| SGA with EFW >10th centile | 153 (12.8%) | 81 (8.4%) | 72 (39.3%) | < .05 |
| Birthweight of babies with EFW >10th centile | 3262 (±636) | 3435 (±451) | 3161 (±624) | < .05 |
| 5-min Apgar <7 | 19 (1.6%) | 11 (1.1%) | 8 (4.0%) | < .05 |
| Stillbirths | 8 (0.6%) | 6 (0.6%) | 2 (1.4%) | .453 |
| Demographic | Total (n = 1234) | AGA (n = 1050) | SGA (n = 184) | Significance between AGA and SGA |
|---|---|---|---|---|
| Maternal age | 30.0 (±5.5) | 30.5 (±5.4) | 29.0 (±5.9) | < .05 |
| BMI | 25.31 (±5.3) | 25.5 (±5.3) | 24.3 (±5.1) | < .05 |
| Ethnicity | ||||
| Caucasian | 751 (60.8%) | 668 (67.9%) | 83 (45.1%) | < .05 |
| Afro-Caribbean | 185 (14.9%) | 158 (16.1%) | 27 (14.7%) | .637 |
| Asian | 287 (23.2%) | 207 (21.0%) | 80 (43.5%) | < .05 |
| Other | 9 (0.7%) | 7 (0.6%) | 2 (1.0%) | .593 |
| Nulliparous, n (%) | 683 (55.3%) | 565 (54%) | 118 (64%) | .518 |
| First- and second-trimester variables | ||||
| PAPP-A MoM | 1.18 (0.7–1.42) | 1.65 (0.74–1.43) | 1.12 (0.60–1.54) | < .05 |
| BhCG MoM | 1.20 (0.6–1.47) | 1.23 (0.65–1.48) | 1.06 (0.64–1.29) | .144 |
| Mean UtA PI | 0.89 (±0.42) | 0.86 (±0.24) | 1.03 (±0.32) | < .05 |
| Scan assessment at RFM presentation | ||||
| Gestational age first episode of RFM | 38.5 (36.6–40.2) | 38.6 (37.0–40.2) | 37.5 (36.1–39.5) | < .05 |
| EFW first episode of RFM | 3240 (±640) | 3342 (±590) | 2672 (±592) | < .05 |
| EFW centile first episode of RFM | 55.7 (34.5–75.4) | 60.9 (42.6–77.5) | 20.0 (11.8–35.1) | < .05 |
| Outcome at birth | ||||
| Gestational age delivery | 40.4 (39.4–41.2) | 40.5 (39.4–41.2) | 38.6 (38.5–41.0) | < .05 |
| Birthweight | 3367 (±508) | 3497 (±425) | 2660 (±296) | < .05 |
| Birthweight centile | 39.7 (19.0–67.0) | 50.5 (±26) | 4.7 (2.7–7.1) | < .05 |
| 5 min Apgar <7 | 19 (1.5%) | 10 (1.0%) | 9 (4.9%) | < .05 |
| Indication, n = 473 | n (%) |
|---|---|
| RFM | 110 (23.2) |
| SGA | 44 (9.3) |
| Prelabor rupture of membranes | 28 (5.9) |
| Pregnancy-induced hypertension | 37 (7.8) |
| Preeclampsia | 13 (2.7) |
| Suboptimal fetal assessment by amniotic fluid, cCTG | 16 (3.3) |
| Maternal disease, eg: chronic hypertension, diabetes, pregnancy cholestasis | 24 (5.0) |
| Others | 5 (1.0) |
| Missing data | 6 (1.2) |
The prevalence of SGA fetuses at the time of first episode of RFM calculated from the ultrasound estimated fetal weight centiles was significantly different for women presenting with single (2.0%) vs repeated (7.8%, P < .05) RFMs. The overall prevalence of SGA at birth in the cohort of patients with and without RFMs was 15.6% (184/1182) and 7.3% (1601/21,944), respectively. The prevalence of SGA birth in women presenting with a single or repeated episodes of RFM was 9.8% (96/983) and 44.2% (88/199), respectively (odds ratio [OR], 7.3; 95% confidence interval, 5.1–10.4; P < .05 between the 2 groups).
Compared to women with a single episode of RFM, those presenting with repeated RFM had higher midpregnancy UtA Doppler PI and gave birth to babies with lower 5-minute Apgar scores. In the cohort of women presenting with RFM, women of Caucasian ethnicity were less likely to represent with repeated RFMs than those of Asian or Afro-Caribbean ethnicity. Compared to women who gave birth to appropriate-for-gestational-age babies, the cohort of women with SGA babies were more likely to be younger, to have a lower BMI, and to be of Asian ethnicity and had higher midpregnancy UtA Doppler indices. No significant correlation was seen between SGA birth at term and first-trimester PAPP-A levels in this cohort.
Logistic regression analysis to assess the relation between maternal and pregnancy characteristics with SGA and repeated episode of RFM are shown in Table 4 . Midpregnancy UtA Doppler PI was the only ultrasound parameter significantly associated with both SGA and repeated episodes of RFM at term. Logistic regression analysis demonstrated no significant associations between first-trimester PAPP-A levels, BMI, or ethnicity with either RFMs or SGA at term.
