Conceived and designed the experiments: AH SR LB RJ CS JF. Performed the experiments: AH LW RJ GB PD DG. Analyzed the data: AH SR. Contributed reagents/materials/analysis tools: DG AH CS. Wrote the paper: PD LW SR GB LB DG RJ JK CS JF AH. Database management and data validation: JK.
The authors have declared that no competing interests exist.
Maternal perception of reduced fetal movement (RFM) is associated with increased risk of stillbirth and fetal growth restriction (FGR). RFM is thought to represent fetal compensation to conserve energy due to insufficient oxygen and nutrient transfer resulting from placental insufficiency.
To identify predictors of poor perinatal outcome after maternal perception of reduced fetal movements (RFM).
Prospective cohort study.
305 women presenting with RFM after 28 weeks of gestation were recruited. Demographic factors and clinical history were recorded and ultrasound performed to assess fetal biometry, liquor volume and umbilical artery Doppler. A maternal serum sample was obtained for measurement of placentally-derived or modified proteins including: alpha fetoprotein (AFP), human chorionic gonadotrophin (hCG), human placental lactogen (hPL), ischaemia-modified albumin (IMA), pregnancy associated plasma protein A (PAPP-A) and progesterone. Factors related to poor perinatal outcome were determined by logistic regression.
22.1% of pregnancies ended in a poor perinatal outcome after RFM. The most common complication was small-for-gestational age infants. Pregnancy outcome after maternal perception of RFM was related to amount of fetal activity while being monitored, abnormal fetal heart rate trace, diastolic blood pressure, estimated fetal weight, liquor volume, serum hCG and hPL. Following multiple logistic regression abnormal fetal heart rate trace (Odds ratio 7.08, 95% Confidence Interval 1.31–38.18), (OR) diastolic blood pressure (OR 1.04 (95% CI 1.01–1.09), estimated fetal weight centile (OR 0.95, 95% CI 0.94–0.97) and log maternal serum hPL (OR 0.13, 95% CI 0.02–0.99) were independently related to pregnancy outcome. hPL was related to placental mass.
Poor perinatal outcome after maternal perception of RFM is closely related to factors which are connected to placental dysfunction. Novel tests of placental function and associated fetal response may provide improved means to detect fetuses at greatest risk of poor perinatal outcome after RFM.
Despite advances in obstetric care stillbirth remains a significant complication of pregnancy. In some high-income countries including the UK and USA there has been little reduction in stillbirth over the past 20 years
Further studies are required to determine the most effective screening strategy for women with RFM to identify which women merit more intensive surveillance or delivery to prevent stillbirth. The ability of clinical history and examination to predict poor pregnancy outcome was assessed in a retrospective study of over 200 cases of RFM. In that cohort, the incidence of small for gestational age (SGA) infants was 24% and stillbirth 1.5%; all stillborn infants were severely growth restricted (birthweight <1st centile)
We aimed to identify clinical predictors of infants at greatest risk of stillbirth after maternal presentation with RFM. We aimed to assess maternal clinical variables, ultrasound fetal biometry, liquor volume and umbilical artery Doppler blood flow and measurement of placentally-derived factors in maternal serum. We have recently demonstrated that RFM is associated with abnormal placental structure and impaired placental function
Ethical approval for the study was obtained from Oldham Research Ethics Committee (08/H1011/83). Women attending the Maternity Day Unit at St Mary's Hospital, Manchester, UK were approached to participate in the study between August 2009 and October 2010 if this was their first presentation with maternal perception of RFM after 28 weeks of gestation in a singleton pregnancy. Women were excluded if the fetus was known to have a structural anomaly, this was a multiple pregnancy, they were unable to give written informed consent or if this was their first contact with the maternity service. A fetal heart trace was performed for 40 minutes to exclude immediate fetal compromise. Provided urgent delivery was not required, written informed consent was obtained and clinical details were recorded from mother's notes including: maternal demographics, details of the duration of RFM, past obstetric and medical history and clinical assessment of symphysiofundal height. The cardiotocograph (CTG) was classified as normal if the baseline rate was 110–160 beats per minute (bpm), the variability was greater than 5 bpm, there were accelerations present and there were no decelerations. If these features were not present the CTG was classified as abnormal
An ultrasound scan was performed to measure estimated fetal weight (calculated from head circumference, abdominal circumference and femur length as previously described
Following delivery, the pregnancy outcome, mode of delivery and any maternal or neonatal postnatal complications were recorded including: birthweight, Apgar scores, umbilical arterial and venous pH (individual data fields are provided in
Serum was obtained from maternal venous blood by centrifugation at 3,000 g for 10 minutes at 4°C; the supernatant was removed at centrifuged at 4,000 g for 10 minutes. 200 µl aliquots of maternal serum were then frozen at −80°C until use. Human chorionic gonadotrophin (hCG) was measured in fresh serum by electrochemiluminescence (Roche E170 analyser, Roche, UK). Lactate dehydrogenase (LDH) activity was assessed by the rate of decrease in NADH (Roche Modular P Unit, Roche, UK). Human placental lactogen (hPL), pregnancy associated plasma protein A (PAPP-A), progesterone and alpha fetoprotein (AFP) were measured by enzyme linked immunosorbent assay (ELISA (Immunodiagnostic systems, Boldon, UK)). Ischaemia modified albumin (IMA) was measured using Albumin Cobalt Binding (ACB®) Test (Inverness Medical Professional Diagnostics Co, USA) and Roche COBAS MIRA® Plus chemistry analyser (Roche Diagnostics, UK) as previously described
To relate the levels of placentally-derived factors to placental structure or function the placenta was collected if women gave birth within 7 days of presentation with RFM. The placenta was collected within 30 minutes of birth and the placenta disc trimmed by removal of cord and membranes and then weighed. Three placental samples were taken, one from the centre of the disc, another from the edge and one from the middle of these two points. The tissue was washed, treated with RNA later (Ambion, UK) and snap frozen at −80°C. Villous tissue from each region was pooled and RNA extracted using TRI reagent (Sigma-Aldrich, Poole, UK). Contaminating genomic DNA was removed by treatment with DNAse (DNA-free kit, Ambion). RNA purity was verified by UV spectroscopy and quantified using Ribogreen (Invitrogen, UK). cDNA was reverse transcribed from 250 ng RNA by AffinityScript cDNA synthesis kit in duplicate reactions to overcome inherent variability (Agilent, UK). Real time PCR for housekeeping gene YWHAZ was performed on cDNA replicates using the following primers: forward –
The power calculation for the sample size was based on the assumption that patients who had poor pregnancy outcome would have similar blood levels of placentally-derived proteins to those described in FGR
Statistical analysis was performed using R (R Foundation for Statistical Computing, Austria). Continuous variables were compared using Mann-Whitney U test or Students' t-test dependent on the distribution of data. Where data were not normally distributed, the variables were logarithmically transformed prior to logistic regression. Logistic regression was used to quantify the effects of potentially prognostic variables on poor outcome, both univariate models and models adjusting for previously described predictors of poor outcomes (gestation, diastolic blood pressure, estimated fetal weight centile, liquor volume and cigarette smoking) were fitted in addition to other statistically significant factors in univariate analysis (abnormal CTG, number of fetal movements normalised to 45 minutes).
During the study period 7,651 women gave birth at the participating unit. 351 women with RFM (4.6%) met the inclusion criteria and were approached to participate in this study. Forty-six women declined and 305 women gave written consent (
Maternal Characteristic | Participants recruited (n = 305) | Non-consenters (n = 46) | p value |
Age | 28 (17–46) | 28 (18–43) | 0.77 |
BMI | 25.2 (17.2–52.8) | 24.0 (18.1–44.1) | 0.20 |
Gravidity | 2 (1–9) | 2 (1–8) | 0.97 |
Parity | 1 (0–7) | 1 (0–4) | 0.79 |
Ethnicity | |||
|
4 (1.3%) | 5 (10.9%) | p<0.001 |
|
29 (9.5%) | 4 (8.7%) | |
|
17 (5.6%) | 3 (6.5%) | |
|
3 (1.0%) | 1 (2.2%) | |
|
171 (56.1%) | 7 (15.2%) | |
|
9 (3.0%) | 3 (6.5%) | |
|
15 (4.9%) | 3 (6.5%) | |
|
16 (5.2%) | 1 (2.2%) | |
|
38 (12.5%) | 18 (39.1%) | |
|
3 (1.0%) | 1 (2.2%) | |
Cigarette smokers | 43 (14.1%) | Not recorded as declined to participate | N/A |
Gestation at Presentation (weeks+days) | 36+2 (28+0–42+0) | 38+3 (28+6–41+2) | 0.003 |
Duration of RFM (hours) | 48 (3–1690) | 24 (5–168) | 0.001 |
History of absent fetal movements | 110 (36.1%) | 7 (21.7%) | 0.004 |
Duration of absent fetal movements (hours) | 7 (2–96) | 14 (10–48) | 0.86 |
Average number of movements in 45 minutes | 9 (0–72) | Not recorded as declined to participate | N/A |
Pregnancy Outcome | Participants (n = 303) | Non-consenters (n = 40) | p value |
Gestation at delivery (weeks+days) | 40+1 (29+0–42+4) | 40+2 (38+0–41+4) | 0.36 |
Birthweight (g) | 3380 (850–5080) | 3240 (2480–3940) | 0.21 |
Birthweight centile | 34 (0–100) | 39 (3–95) | 0.85 |
The median reported duration of RFM at presentation was 48 hours, although there was a wide range from 3 hours to over 1 week; 36.1% of participants reported absent fetal movements for a period of time. When women were on the fetal heart rate trace for 45 minutes, the median number of movements recorded was 9, ranging from 0 to 72. At the time of presentation with RFM, a clinical history was taken. Forty-three women (14.1%) reported smoking cigarettes, ranging from 2–20 cigarettes/day, 7 (2.3%) women reported drinking alcohol, ranging from 1–6 units per week. Thirty-six women (11.8%) had significant past medical history including: anaemia, asthma, epilepsy, hypothyroidism, hypertension and thrombophilia. Fifteen of the 157 (9.6%) parous women had significant past obstetric history including: FGR, placental abruption, preeclampsia, preterm birth, stillbirth and SGA infants. Measurement of maternal blood pressure found 5 participants were hypertensive with a blood pressure >140/90 mmHg and two participants had significant proteinuria (≥2+) on urine dipstick. Twelve women (4%) had a non-reassuring fetal heart rate trace, in four women these changes became pathological necessitating emergency Caesarean section. At ultrasound scan, 1 case had absent end-diastolic flow detected by umbilical artery Doppler, 14 cases had oligohydramnios and 29 cases had an estimated fetal weight ≤10th centile.
Two hundred and thirty-six participants (77.9%) had a normal outcome compared to 67 who had a poor outcome (22.1%). Of those with poor outcome, 7 were preterm (with birthweight >10th centile, 4.1%), 2 term infants were admitted to NICU (0.7%), and 51 (16.8%) were SGA at term and 7 (2.3%) were SGA preterm (
Pregnancy Outcome | Number | % |
Normal | 236 | 77.9 |
Preterm (normal weight) | 7 | 2.3 |
Small for gestational age (Preterm) | 7 | 2.3 |
Small for gestational age (Term) | 51 | 16.8 |
NICU admission for Perinatal Asphyxia | 2 | 0.7 |
Total | 303 | 100 |
Small for gestational age was defined as a birthweight less than 10th centile.
The concentrations of hCG, hPL and progesterone were significantly lower in women who had poor perinatal outcome following RFM compared to those with normal outcomes. There was no difference in AFP, IMA, LDH or PAPP-A between women with poor perinatal outcome and those with normal outcomes (
A) human chorionic gonadotrophin (hCG), B) human placental lactogen (hPL), C) progesterone, D) alphafetoprotein (AFP), E) Ischemia-modified albumin (IMA), F) Lactate dehydrogenase (LDH) and G) Pregnancy-associated plasma protein A (PAPP-A). * p<0.05, ** p<0.01, ***p<0.001.
A) serum hCG was not related to placental weight, B) There was no difference between hCG mRNA and pregnancy outcome, C) serum hPL positively correlated to placental weight (*** p<0.001), D) There was no difference between hPL mRNA expression and pregnancy outcome, E) serum progesterone positively correlated to placental weight (** p<0.01), F) There was no difference between 3β-HSD mRNA expression and pregnancy outcome.
Univariate logistic regression demonstrated a significant relationship between poor pregnancy outcome and the number of movements felt during the fetal heart rate trace, abnormal fetal heart rate trace, diastolic blood pressure, estimated fetal weight centile, liquor volume, log [hCG] and log [hPL] (
Variable | Median (range) or |
Crude Odds Ratio | Confidence Interval | p value | Adjusted Odds Ratio |
Confidence Interval | p value |
Gestation at presentation (days) | 254 (196–294) | 1.00 | 0.99–1.01 | 0.29 |
|
|
|
Gestation at presentation <37 weeks |
|
0.97 | 0.92–1.01 | 0.14 |
|
|
|
Maternal Age | 28 (17–46) | 1.00 | 0.95–1.05 | 0.95 | 1.04 | 0.98–1.10 | 0.24 |
Maternal BMI | 25.2 (17.2–52.8) | 0.98 | 0.94–1.03 | 0.46 | 1.01 | 0.95–1.08 | 0.71 |
Gravidity | 2 (1–9) | 0.93 | 0.77–1.12 | 0.43 | 0.97 | 0.77–1.23 | 0.82 |
Parity | 1 (0–7) | 0.94 | 0.72–1.13 | 0.63 | 0.99 | 0.72–1.37 | 0.95 |
Smoking (Yes/No) |
|
1.96 | 0.96–4.00 | 0.06 | 1.55 | 0.55–3.68 | 0.32 |
Alcohol (units/week) | 0 (0–6) | 0.77 | 0.31–1.87 | 0.56 | 0.72 | 0.19–2.68 | 0.62 |
Duration of RFM (hours) | 48 (3–1690) | 1.00 | 1.00–1.01 | 0.55 | 1.00 | 0.99–1.00 | 0.55 |
Significant Medical History (Yes/No) |
|
1.01 | 0.44–2.33 | 0.99 | 0.88 | 0.32–2.46 | 0.81 |
Significant Obstetric History (Yes/No) |
|
1.35 | 0.40–4.53 | 0.63 | 1.61 | 0.36–7.35 | 0.54 |
FMs normalised to 45 minutes | 9 (0–72) |
|
|
|
0.98 | 0.95–1.02 | 0.28 |
Abnormal CTG (Yes/No) |
|
|
|
|
|
|
|
Further episodes of RFM (Yes/No) |
|
1.15 | 0.91–1.46 | 0.24 | 1.03 | 0.75–1.42 | 0.86 |
Systolic blood pressure (mmHg) | 110 (80–150) | 1.02 | 1.00–1.04 | 0.078 | 1.00 | 0.96–1.04 | 0.92 |
Diastolic blood pressure (mmHg) | 60 (50–114) |
|
|
|
|
|
|
Estimated fetal weight centile | 53 (0–100) |
|
|
|
|
|
|
Amniotic fluid index (cm) | 125 (10–252) |
|
|
|
0.99 | 0.98–1.00 | 0.13 |
Maximum pool depth (cm) | 51 (0–133) |
|
|
|
0.99 | 0.96–1.01 | 0.28 |
Abnormal Umbilical Artery Doppler |
|
NA |
NA |
NA |
NA |
NA |
NA |
Umbilical Artery Pulsatility Index | 0.8 (0.5–1.4) | 3.29 | 0.75–14.42 | 0.12 | 2.96 | 0.38–23.21 | 0.30 |
Log hCG | 4.20 (2.85–5.09) |
|
|
|
0.88 | 0.32–2.46 | 0.81 |
Log hPL | 2.54 (2.15–3.12) |
|
|
|
|
|
|
Log IMA | 1.97 (1.42–2.14) | 0.60 | 0.22–1.61 | 0.31 | 0.53 | 0.04–7.91 | 0.65 |
Log LDH | 2.70 (2.36–2.94) | 2.67 | 0.70–10.17 | 0.15 | 5.42 | 0.11–278.74 | 0.40 |
Log PAPP-A | 2.67 (1.63–4.52) | 0.94 | 0.77–1.14 | 0.50 | 0.78 | 0.44–1.38 | 0.39 |
AFP | 70.9 (1.7–232.2) | 0.99 | 0.99–1.00 | 0.23 | 0.99 | 0.99–1.00 | 0.13 |
Progesterone | 369.1 (167.9–777.8) | 0.99 | 0.99–1.00 | 0.079 | 1.00 | 1.00–1.00 | 0.73 |
Adjusted for gestation, number of fetal movements normalised to 45 minutes, abnormal CTG, diastolic blood pressure, estimated fetal weight centile, maximal pool depth and smoking status.
only calculated for parous participants.
Odds ratios could not be calculated as only one infant had abnormal umbilical artery Doppler at initial assessment.
When multivariate regression was performed, adjusting for previously reported predictors of fetal wellbeing, the following factors remained predictors of poor perinatal outcome: diastolic blood pressure, estimated fetal weight centile and log [hPL]. Of the 67 poor perinatal outcomes, 4 were identified by cardiotocography, 20 by ultrasound assessment of fetal growth, liquor volume and umbilical artery Doppler, and a further 24 by low hPL in the absence of other abnormality. hPL values less than 1 standard deviation below the mean value for any given gestation was associated with a odds ratio for poor pregnancy outcome of 4.91 (95% CI, 2.8–8.67).
These data confirm the link between RFM and increased incidence of pregnancy complications including SGA, FGR and fetal hypoxia as shown in earlier studies
It is hypothesised that RFM is linked to FGR and stillbirth as a clinical manifestation of the fetus reacting to nutrient and oxygen deprivation secondary to placental insufficiency
The association between hPL and poor pregnancy outcome does not necessarily indicate that this marker will have clinical value, but it does suggest that novel placental function tests merit further investigation in the clinical management of RFM. Recently, a similar strategy using placental growth factor (PlGF) has been successfully employed to differentiate babies that have pathological FGR from those who are constitutionally small in the third trimester of pregnancy
This prospective study is limited by the absence of stillbirths from the observed perinatal outcomes. Importantly, four infants were delivered by emergency Caesarean section for fetal compromise. If this intervention had not been employed these infants would likely have died
This study did not employ a standard definition of RFM because there is no evidence-based definition of RFM that performs better than maternal perception of RFM alone
The finding that estimated fetal weight centile has the strongest association with poor perinatal outcome following RFM supports the findings of a care-improvement project in Norway in which ultrasound assessment of fetal size and liquor volume in women with RFM was associated with a reduction in stillbirth rate
Nevertheless, a more efficient strategy is needed to predict which pregnancies are most at risk of stillbirth after maternal perception of RFM as a single ultrasound scan has a sensitivity of 33.3% to detect SGA and CTG can give false reassurance which may increase perinatal mortality in low-risk populations
(DOC)
The authors would like to thank women who participated in this study and for the midwives at St Mary's Hospital for their assistance in participant recruitment and data collection after birth.