Evolving pattern of fetal movements throughout a healthy pregnancy

Abstract

A 31-year-old woman with a history of stillbirth due to placental abruption at 29 weeks’ gestation and one first trimester miscarriage documented a continuous record of her perceived fetal movements from 28 to 38 weeks’ gestation. Repeated ultrasound examinations confirmed a viable pregnancy, with normal growth, liquor volume and Doppler profile. She delivered a healthy male infant at 38 weeks and 3 days’ gestation. The data collected give a detailed record of fetal activity in a healthy pregnancy. Perceived fetal activity increased as pregnancy progressed and was greatest in the evenings. We also found that clusters of movements, which have previously been reported as protective against stillbirth, were felt earlier on in pregnancy.

Background

Perception of fetal movements is a reassuring feature of fetal well-being to both the mother and health professionals. Reduced movements can be a sign of placental dysfunction^{1 2}; the reduction in movements is hypothesised to be a response to conserve energy by moving less.³ Most women are aware of fetal movements between 18 and 20 weeks’ gestation. Currently, women are asked to observe their pattern of movements from 28 weeks’ gestation and if they are reduced seek medical advice.⁴

A recent study has shown a diurnal pattern in strength and frequency of fetal movements perceived by the mother, with an increase in both aspects during the evening. Late stillbirth odds have been shown to quadruple in women who report quieter movements in the evening. The study also found that ‘clusters’ of movements reduced the odds of stillbirth.⁵

Up to 55% of women who have a pregnancy resulting in stillbirth report reduced fetal movements in the previous week.⁶ The AFFIRM trial (Awareness of Fetal movements and care package to reduce Fetal Mortality) found that increased maternal awareness of fetal movements in combination with intervention based on reduced movements was only marginally beneficial in reducing the rate of stillbirth and led to increased rates of intervention which may be harmful.⁷ One challenge of providing information about ‘normal’ fetal activity is the lack of data from healthy uncomplicated pregnancies, and the lack of an evidence-based ‘alarm limit’. Here, we report a detailed profile of fetal movements from one woman, with a history of stillbirth, from 28 weeks until she gave birth at 38 weeks’ gestation. We were able to use these very detailed data to look at her daily pattern and how these movements changed as pregnancy progressed.

Case presentation

A 31-year-old woman attended the Rainbow Clinic (a clinic developed for women who have experienced a previous neonatal death or stillbirth), in her third pregnancy. She had a history of a fetal death in utero, which had been an uncomplicated pregnancy up until 29 weeks and 1 day when she attended with abdominal pain and bleeding. Fetal death in utero was diagnosed and following induction of labour and delivery of a stillborn female infant a diagnosis of placental abruption was made. Postmortem and placental histology were subsequently normal. Her second pregnancy ended in a missed miscarriage at 10 weeks’ gestation, with chromosomal analysis confirming Trisomy 22. Both parental karyotypes were found to be normal.

In the patient’s third pregnancy she had regular ultrasound scans from 22 weeks and 4 days which showed an estimated fetal weight of 604 g (between 50th and 90th centile), normal liquor volume (amniotic fluid index 5.6 cm) and umbilical artery Doppler waveform (Pulsatility Index (PI) 1.11) and mean uterine artery PI was 0.67. There was no notching of the uterine arteries. Regular ultrasound scans confirmed normal growth profile, liquor and umbilical artery Doppler waveforms. She delivered a live born male infant at 38 weeks and 3 days, birth weight 3406 g with Apgar scores of 9 at 1 min and 10 at 5 min. He was not admitted to the special care baby unit. During her pregnancy, the patient maintained a continuous record of every fetal movement felt from 28 weeks’ gestation onwards broken down by time of day. Data were extracted from these records to provide a detailed view of fetal activity in this healthy pregnancy.

Outcome and follow-up

The patient recorded a total of 9946 movements over the 10-week period from 28 to 37 weeks and 6 days’ gestation. The woman’s waking hours were 06:00–23:00 and evenings were between 17:00 and 23:00. We analysed perceived movements during these periods, including how they changed throughout the day and as gestation increased. The average number of daily fetal movements increased from 32 weeks’, from an average of 101 movements per day <32 weeks’ to 182 by 37 weeks’ gestation (figure 1A). From 37 weeks and 1 day, the patient reported an average of 218 movements per day. There was an average of 12.8 movements per waking hour after 37 weeks’ gestation. A cluster of movements was classified as five movements in quick succession. The woman recorded more clusters of movements earlier on in pregnancy and by the end of 32 weeks’ gestation reported two or less clusters per day (figure 1B).

Figure 1.

(A) Graph of average number of movements per day per week of pregnancy showing increase in the number of movements as pregnancy progresses. (B) Graph of average number of cluster of movements per day showing these were felt earlier in pregnancy. (C) Graph of average number of movements felt per hour of the day each week demonstrating an increase in movements in the evening and towards the end of pregnancy. (D) Graph of average number of movements felt per day when the woman was busy showing an inverse relationship. (E) Graph of average number of hours baby active when the woman was busy showing that fetal movements were still felt when attention was not paid solely to movements.

Fetal movements increased in the evening at all stages of her pregnancy (figure 1C). By 37 weeks’ gestation the woman reported an average of 62 movements early morning (06:00–09:00) compared with 105 movements in the evening (17:00–23:00). As movements increased as the pregnancy progressed, the woman reported an average of 31 movements in the evening at 32 weeks’ gestation compared with 105 movements in the evening at 37 weeks’ gestation. The average number of movements by 38 weeks’ gestation was 102, compared with 105 at 37 weeks’ gestation. The data were examined to see if the number of perceived movements were affected by days where the patient was busy and less able to record numbers of movements. This found that the more occupied the patient was, the fewer movements she recorded (figure 1D). On days where the patient was busy, she still recorded if activity was felt. However, the baby was active on average 16 hours per day both when she was not busy and when she reported being busy for 9 hours that day.

Discussion

There are scarce data for fetal movement patterns in a normal pregnancy and there is no agreed definition of a ‘normal pattern’ which hinders understanding of reduced or abnormal fetal activity. This case provides a high level of individual detail that illustrates findings documented by early epidemiological studies; that fetal movements increased as the pregnancy progressed, and more movements were felt in the evenings. We also found that ‘clusters’ of movements were felt earlier on in pregnancy.

There are various factors influencing the perception of movements. Despite being unable to document exact numbers of movements during times she was busy, this woman recorded whether or not movements were felt at all. Johnson found that when attention is paid solely to fetal activity, movements are felt which were not previously perceived.⁸ Analysis of our data helped determine that perceived movements were inversely related to the number of hours the patient was busy. Other factors which may influence the perception of movements include increased anxiety in pregnancy after a loss,⁹ an anterior placenta and fetal position.⁹

The current Royal College of Obstetrics and Gynaecology(RCOG) Guideline for Reduced Fetal Movements describes fetal movements increasing until 32 weeks’ gestation then plateauing. This is supported by multiple studies suggesting that although the strength of movement may increase as pregnancy progresses, the frequency remains the same.^{10 11} Increased fetal movements in later pregnancy have been found to be a sign of fetal well-being.¹² By term, there is an average of 31 movements per hour, ranging from 16 to 45. Our data agree that movements increase up until 32 weeks’, however, in this case, perceived movements continued to increase until term.

Our findings show a clear diurnal pattern in fetal movements throughout the whole of pregnancy, in keeping with the RCOG guidance. This is further supported by a study by Bradford et al which looked at the fetal movements of 274 pregnancies which found 74.5% of women reported increased fetal movements in the evening.⁵ Interestingly, Moore and Piacquadio focused on counting to 10 movements in the evenings which reduced the rate of perinatal mortality which has not been found in other studies. This raises the question whether movements have more significance at this time of day.¹³ Another interesting finding from this data was the reported clusters of movements earlier in late pregnancy. Clusters of movements have previously been found to be protective against stillbirth, however, were found to remain either unchanged or prolonged as the pregnancy progressed by Bradford et al. These ‘busy periods’ may benefit from further study to further determine how best to describe them to pregnant women and their absence may be perceived negatively by women.

As there is insufficient evidence to suggest an inclusive ‘alarm limit’ for both low-risk and high-risk pregnancies, more data is required to provide a definition of a ‘normal pattern of fetal movements’ in pregnancies with a healthy outcome. Guidelines emphasise the need to seek advice with deviation from individual patterns; it appears that this awareness is more important than a fixed number. To aid the clinician to recognise individual patterns, advanced technology could be of use. There are multiple easily accessible mobile phone applications in which women can record their daily perceived movements. This could help both patients and healthcare professionals establish an individual pattern and define a reduction in fetal movements.

Patient’s perspective.

I recorded every movement in the pregnancy after my daughter was stillborn because I didn’t trust that my body was capable of a successful pregnancy and I spent the entire pregnancy seeking reassurance that everything would be ok. I craved some tangible proof that the baby was ok and that is what the movement monitoring provided. I also found the messages (from midwives, pregnancy literature, etc) about the need to monitor movements quite stressful because I was terrified that I would miss something. Essentially, I just wanted proof everything was ok.

The movement records provided me with proof that the baby was moving. I’m a visual learner and it was helpful to see some evidence in front of me of what the movements were like each day. I still made numerous trips to my local maternity triage but I honestly think the number of these was less because the records gave me confidence that everything was as it should be. It was also helpful to have something to show to doctors and midwives to check if the baby was moving ‘enough’. Although it was time-consuming, it was better for me to put my time and energy into creating evidence to show everything was ok than to spend the time worrying that something was wrong, which is what I was doing before I started recording the movements. Interestingly, I never identified any obvious patterns other than that I felt more movements in the evenings.

Learning points.

• Individual data of perceived fetal movements provides evidence of a pattern to fetal activity.

• There were more perceived fetal movements in the evening throughout pregnancy.

• Perceived movements increased as the pregnancy progressed and were decreased when the woman was busy with other activities.

• There was 10-fold variation in the number of movements per hour within 1 day making the development of standardised alarm limits for reduced activity difficult.

• Technology (eg, mobile phone apps) could be used to record an individual woman/baby’s movements to define reduced fetal movements.