http://doi.org/10.33698/NRF0193 – Varsha, Sukhjit Kaur, Pardip Kaumar Saha
Abstract : In last trimester of pregnancy non stress test is a part of prenatal diagnosis to monitor fetal wellbeing. It monitors the response of fetal heart rate to the fetal movements. The current study was undertaken with an objective to assess the effect of left lateral and sitting position of mother on reactivity and time consumption of non stress test, using comparative design. Total 100 antenatal mothers above 32 weeks of gestation visiting obstetrics and Gynae OPD, PGI, Chandigarh were enrolled by total enumeration sampling technique. Each mother was first given left lateral position followed by sitting position after 10 to 30 minutes. Non stress test Graphs were observed for fetal heart rate, baseline heart rate, variability and acceleration in both positions. Result showed that non stress test performed in left lateral position significantly required less time to achieve reactivity as compared to sitting position. Whereas no significant difference in reactivity of non stress test in left lateral and sitting position was observed. Out of 100 subjects, only one subject showed non reactive stress test. Majority (64%) of antenatal mothers reported to be comfortable in left lateral position. So it is concluded that left lateral position is more preferable during non stress test and it can be applied in daily practice for time effective evaluation and also in terms of comfort.
Keywords
Non stress test, baseline heart rate, variability, acceleration.
Correspondence at
Dr Sukhjit Kaur
Clinical Instructor
National Institute of Nursing Education, PGIMER, Chandigarh
Introduction
Antenatal care is one of an important element to ensure normal pregnancy with delivery of healthy baby. There are many ways to evaluate the health and well-being of a developing baby (fetus) throughout pregnancy. If a woman has a pregnancy at higher risk for complications, certain investigations can be done to check the fetal well being. Prenatal investigations are done to see if the baby is receiving enough oxygen and nourishment through placenta1. Fetal heart rate is an integral part of fetal surveillance. Auscultation of fetal heart rate has been a standard component of each prenatal visit. Monitoring fetal heart rate pattern is called non stress test. Non stress test is basically an electronic monitoring of fetal heart rate response to the fetal movements. The goal of non stress test(NST) is to determine whether the intrauterine environment continues to be supportive for the fetus. Fetal heart rate variability or rhythmic changes in baseline heart rate is reassuring indicator of supportive intrauterine environment2.
There are certain factors that affect the reactivity as well as time to achieve reactivity during non stress test i.e Maternal Position, Diet, Exercise, manual stimulation, vibroacoustic stimulation, sleep cycle of baby.Fetal movements are usually absent during fetal “sleep” cycles. These quiet cycles occur regularly throughout the day and night and usually last 20– 40 minutes Sleep cycle rarely exceeds 90 minutes in the normal, healthy fetus3. However, the maternal position during the testing is an important element that should be part of practice guidelines. Pregnant women are generally positioned in the supine position because this position allows easy administration of the test. But supine position causes aortocaval compression which decreases blood supply to the fetus hence shows non reactive results. Hence Position is one of the main factors which should be considered during non stress test. Proper positioning of the mother during the test can eliminate procedure related errors and will prevent false interpretation. Literature recommends either left lateral tilt position, semi fowlers, or sitting position for antenatal mothers during non stress test. A study done in New York, to determine whether maternal posture (left lateral recumbent vs semi- Fowler position) had any effect on non- stress test results. As per findings, it was recommended that semi-Fowler position is a superior position for conducting a non stress test in a short period4. Another study on 368 antenatal mothers compared reclining and sitting position during NST and revealed that sitting position or walking should be encouraged during non stress test because fetal reactivity is more quickly observed5. Studies shows that, left lateral and sitting position are preferable but it is still an open question regarding the best position during non stress test in terms of reactivity and time consumption. This inspired the researcher to take up present study with the objectives to compare the effect of different positions while performing non stress test in terms of time consumption and reactivity.
Material and method
The study was conducted in obstetrics and Gynae Out Patient Department (OPD) at Post Graduate Institute of Medical Education and Research (PGIMER), Chandigarh. Study population comprises of antenatal mothers above 32 weeks of gestation visiting obstetric and gynecology OPD in the month of July & August 2014. Total enumeration sampling technique was adopted and total 100 antenatal mothers were enrolled after taking written informed consent. Full autonomy was given to the study subjects to participate in research and withdraw any time. Procedure protocol for non stress test in left lateral and sitting position and tools were developed after extensive review of literature and validated by experts from nursing and department of obstetrics and gynecology. The tools included Interview schedule and observation tool which included section A and B. Section A comprised of Identification Performa – It consist of sociodemographic profile and obstetric profile of antenatal mothers and Section B included observational findings of non-stress test.
Interview schedule and observation were used for the data collection. The data was collected in the month of July and August 2014. All the concerned Doctors and Nurses were informed about the study. Data collection was done in Antenatal OPD. The cases were recruited according to the inclusion criteria which included all the antenatal mothers above 32 weeks of gestation willing to participate in the study. The written informed consent was taken. Full autonomy was given to the study subjects to participate in research and withdraw at any time. After collection of Identification data by interview schedule, Non stress test(NST) was performed as per protocol firstly in left lateral position followed by sitting position after 10 minutes. For taking NST antenatal mother was first given comfortable position followed by auscultation of FHR location
.Transducer connected to NST machine was placed over FHR location .Then graph was taken. NST graphs were evaluated for reactivity. The test is reactive if FHR is 120- 160 beats per minute(bpm), BHR (Baseline heart rate) is 110 – 160bpm, 2 accelerations in 20 minutes and variability is 5 to 25. Accelerations are the abrupt increase in fetal heart rate ,which should be more then 15 beats for 15 seconds. Variability less then five or more then 25 indicates fetal distress. NST Graph was observed for baseline heart rate, variability, acceleration, time consumption. Baseline heart rate was calculated by taking average fetal heart rate of 10 readings that doesn’t include accelerations or decelerations of the fetal heart rate.
Collected data was coded and entered in the SPSS (Statistical Package for Social Sciences) 16.0.Version. The analyzed data is presented in the form of tables, figures, and other bar diagrams. Comparison of the outcome variables in left lateral and sitting position is done using paired t test. ‘Chi square’ (McNemar) was used for categorical data.
Results
As per socio demographic data summarized in the table 1, Out of 100 antenatal mothers 47 antenatal mothers were in age group of 20-25 year and 35 in
Table No. 1: Sociodemographic profile of antenatal mother
N= 100
| Variable | N |
| Age( in years)* | |
| 20-25 | 47 |
| 26-30 | 35 |
| 31-35 | 16 |
| 36-40 | 2 |
| Education | |
| Illiterate | 2 |
| Primary | 25 |
| Secondary | 35 |
| Graduate and above | 38 |
| Occupation | |
| Housewife | 86 |
| Working | 14 |
| Religion | |
| Hindu | 59 |
| Sikh | 37 |
| Muslim | 4 |
| Family | |
| Nuclear | 72 |
| Joint family | 28 |
age group of 26 – 30 year. Mean age±SD is 26.4±3.6 years with and in the Range of 21 –
Findings of abdominal palpation of subjects – Out of 100 subjects, majority 38 years. Almost all the mothers (98%) were literate. Majority (86%) were housewife and from nuclear family(72%). 59 antenatal mothers belonged to Hindu religion, 37 Sikh and 4 Muslim religion.
Table 2 depicts that 54% of antenatal mothers were primigravida. 15% of them had gestational diabetes, 5% had placenta previa and 19% had pregnancy induced hypertension.As regard to period of gestation 33% were having 32-35 weeks of gestation, 40% were having 36-38 weeks of gestation and 27% were having 39-41 weeks of gestation.
Table 2: Obstetric variable of subjects
N= 100
| Variable | N |
| Gravida Primigravida Multigravida |
54 46 |
| Obstetric disorder during | |
| present pregnancy | |
| Gestational diabetes | 15 |
| Placenta praevia | 5 |
| Pregnancy induced hypertension | 19 |
| Uterine fibroid | 1 |
| Period of gestation | |
| 32-35 weeks | 33 |
| 36-38 weeks | 40 |
| 39-41 weeks | 27 |
(96) were having cephalic presentation, 99 subjects had longitudinal lie and 1 had transverse lie.In 67 subjects ,fetal head was engaged . Majority(99) of mothers were reported to have fetal movements.Only 1 mother reported to have no fetal movements since morning.
Findings of Non stress test- Table 3 describes comparision of Fetal heart rate, base line heart rate, variability and time consumption in left lateral and sitting positions while performing non stress test. All the subjects had normal fetal heart rate(FHR) and base line heart rate(BHR) i.e between 115-160 beats per minute.It reveals that there is no significant difference found when FHR , BHR compared in left lateral and sitting position.31 subjects in left lateral and 28 subjects in sitting position had fetal heart rate (FHR) in range of 115 – 130 beats per minute. 66 subjects in left lateral and 67 subjects in sitting position had FHR 131-145 bpm. Very few (3) subjects in left lateral and 5 subjects in sitting position had FHR in range of 140-160 bpm. Similarly there was no significant difference in variability. Almost all the (99) subjects showed moderate variability (5-25 bpm). Time consumption for reactive NST in left lateral and sitting position showed significant difference. 88 subject in left lateral and 67 subjects in sitting position had time consumption in range of 5-15 minutes. 11 subject in left lateral and 32 subjects in sitting position had time consumption in range of 16-25 minutes.
Table 3: Fetal heart rate base line heart rate variability in left lateral and sitting position.
N= 100
| Variable | Left lateral position | Sitting position | z2(df)P value |
| Fetal heart rate(Beats/min) 115-130
131-145 146-160 |
31 66 3 |
28 67 5 |
1.64(2)>.05 |
| Baseline heart rate(beats/min) 115-130
131-145 146-160 |
19 72 9 |
22 67 11 |
1.72(2) >.05 |
| Variability
<5 5-25 |
1 99 |
1 99 |
|
| Time Consumption for reactive NST(minutes)
5 – 15 16 – 25* >26* |
88 11 0 |
67 32 1 |
1.25 (1) <0.05 |
*Both rows merged together for calculating z2 test
Table 4 exhibits the comparison of mean time consumption for reactive non stress test in left lateral and sitting position. Mean time taken in left lateral position is significantly less(6.54+2.4) then sitting position(9.39+ 4.21).(p<0.05 as per t test). Hence it proves that left lateral position considerably took less time to achieve reactivity as compared to sitting position of mother.
Table 4 : Comparison of time consumption in left lateral and sitting position
N= 100
| Position | Mean Time (minutes) consumption* Mean ± SD | t(df)
p-value |
| Left lateral | 6.54 ± 2.41 | 5.96 |
| Sitting | 9.39 ± 4.21 | (99) |
| <0.001 |
*Mean time is the time taken to achieve 2 accelerations.
Percepetion of mother regarding comfortable position during non stress test
An attempt has been made to know the perception of antenatal mothers regarding comfortable position during non stress test. position they were comfortable during the non stress test. More than half subjects were in favor of left lateral position during the non stress test whereas only one fourth of the subjects supported sitting position and 10% were comfortable in both position.
Discussion
Antenatal care brings safety to the mother and her baby. Antenatal mothers are advised for minimum three antenatal checkups to bring all obstetric mothers under medical supervision throughout pregnancy. Besides many benefits of antenatal care, fetal well being is assessed and safety of fetus is enhanced to reduce perinatal mortality and morbidity. Non stress test (NST) is the most common and significant test performed for antenatal mothers in late pregnancy to monitor fetal heart rate response to the fetal movements6.
In antenatal clinic of PGIMER, Chandigarh, non stress test is routinely performed for antenatal mothers above 32 weeks of gestation. Based on the findings of non stress test ,fetal well being is estimated. Certain factors which can lead to prolong monitoring of non stress test results, one of them is maternal position. Studies shows that, left lateral and sitting position is preferable but it is still an open question regarding the best position during non stress test in terms of reactivity and time consumption. Performing non stress test in a possible less time could enhance time effective evaluation of antenatal mothers. This fact inspired the researcher to take up present study to compare left lateral and sitting position in terms of time consumption and reactivity.
Since fetal neurological system is not well developed before 24 weeks hence non stress test is performed after 28 weeks. In antenatal OPD of PGIMER Chandigarh, non stress test is regularly performed for all mothers above 32 weeks of gestation. Trace is obtained for 20-30 minutes. If non stress test is non reactive upto 30 minutes antenatal mother will likely undergo another prenatal test. Non reactive test upto 30 minutes might occur because baby’s sleep cycle is 30 to 40 minutes. The basis for performing and interpreting the antenatal non stress test is the belief that the reactive non stress test reflects a well, uncompromised fetus and that certain abnormalities indicate an increased possibility of fetal compromise. Observational studies showed a strong correlation between an abnormal non stress test and poor fetal outcome6. Several factors can contribute to false-positive results and increase the time spent performing tests. One of them is maternal position position during NST influence the hemodynamics of the mothers6.
The results of present study revealed that Mean time taken in left lateral position is considerably less (6.54±2.4) than sitting position(9.39±4.21) (p=<0.05, t=5.96). It shows a significant difference in time consumption. These findings are in accordance with the study done by Sekhavat L et al, to see the effect of different maternal position (supine and lateral position) on non stress Test (NST) (reactivity and time consumption) and to identify alternative positions during the test to provide optimum comfort. Findings revealed that supine position showed less fetal reactivity than lateral position and required more time to achieve reactivity. In left lateral position fetal reactivity was more quickly observed and could decrease the need for prolonged monitoring, thus leading to a more time- effective evaluation of patients at risk.7 These findings are contrary to Alus et al., to assess the effects supine, left lateral, semi- fowler and sitting position on non-stress test. Study reported that there were no statistically significant differences among the four maternal positions (Sitting up, Semi-fowler, Supine left and supine) in terms of time consumtion for reactivity but there were significant (P < 0.05) differences among four groups in terms of reactivity Supine position showed the least fetal reactivity8.
One of the study compared semifowlers and left lateral position during non stress test, concluded that semifowler is a superior position as it decrease the need for prolong monitoring whereas present study compared left lateral and sitting position. The results recommends left lateral position for non stress test in terms of time consumption but no difference seen in reactivity
In present study one subject reported to have absent fetal movements since morning .Non stress test was extended to 40 minutes which showed non reactive results. Further mother was taken for ultrasound and fetus was found viable. In a study done by Froen etal, decreased fetal movement have been shown to be associated with adverse pregnancy outcomes such as intrauterine growth restriction, intrauterine fetal death, neonatal intensive care unit admission, low Apgar scores, and less common developmental anomalies such as those affecting the neuromuscular system9.
Based on the findings of present study it was concluded that left lateral position during non stress test consumed considerably less time to achieve 2 accelerations as compared to sitting position. No difference was seen in terms of reactivity in both the position. In terms of comfort, antenatal mothers reported to be more comfortable in left lateral position. Hence it is recommended that left lateral position should be incorporated during non stress test which could decrease need for prolong monitoring thus lead to time effective evaluation. Study could generate protocol for non stress test which can help the staff nurses to enhance their competences and help pregnant women to be comfortable and consumes lesser time while monitoring non stress test.
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