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 Table of Contents  
Year : 2018  |  Volume : 8  |  Issue : 3  |  Page : 155-158

The four-dimensional ultrasonography effects on changes of foetal and maternal heart rate: Are these interventions safe?

1 Department of Midwifery and Reproductive Health, Shahid Beheshti University of Medical Sciences, Tehran, Iran
2 Department of Radiology, Arak University of Medical Sciences, Arak, Iran
3 Department of Internal Medicine, Arak University of Medical Sciences, Arak, Iran
4 Department of Gynecology, Arak University of Medical Sciences, Arak, Iran
5 Department of Social Medicine, Arak University of Medical Sciences, Arak, Iran
6 Department of Epidemiology and Biostatistics, Research Center for Environmental Pollutants, Qom University of Medical Sciences, Qom, Iran

Date of Web Publication24-Sep-2018

Correspondence Address:
Fatemeh Saafi
Department of Radiology, Vali-Asr Hospital, Arak
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/AIHB.AIHB_26_18

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Background and Objectives: Ultrasonography is one of the prenatal diagnostic methods, which is applied to detect any genetic diseases, defects, and anomalies. This study aimed to evaluate the changes in foetal heart rate (FHR) and maternal heart rate due to four-dimensional (4D) ultrasonography immediately after ultrasound imaging. Materials and Methods: This descriptive study was conducted on the foetus of pregnant women who were referred to the ultrasound clinic for undergoing a (4D) ultrasonography. After filling out the demographic forms, the baseline FHR was measured at the beginning of the 2D and 4D ultrasonography. All haemodynamic parameters were recorded at the end of the combined ultrasound imaging. Data were compared before and after ultrasonography using paired t-test and correlation coefficient in SPSS software. Analysis of covariance (ANCOVA) was used to adjust the effect of baseline heart rate in foetus and sonography. Results: The mean duration of combined 2D and 4D ultrasound imaging was 1249.8 ± 257 s. Moreover, the mean 4D ultrasound duration was 246.1 ± 83.3. A significant decrease were observed in maternal heart rate following the combined ultrasonography (P < 0.001), while the changes in FHR were not significantly different after the ultrasound imaging (P = 0.394). The ANCOVA showed that sonography was not related factors for change in FHR (β = 0.006, 95% confidence interval [CI]: 0.011–0.024, P = 0.467) while the base FHR (β = 0.659, 95% CI: 0.482–0.836, P < 0.001) was directly associated with FHR change. Conclusion: The 4D ultrasonography was not effective factor on the FHR and it seems that the ultrasound imaging is a safe diagnostic method for FHR. However, we recommended long-term studies to evaluate the effect of the 4D ultrasound imaging on preterm labour, post-partum complications, and mental problems.

Keywords: Adverse effects, foetal heart rate, foetus, pregnancy, ultrasonography

How to cite this article:
Naafe M, Saafi F, Larijani HH, Jamilian M, Sadeghi B, Mohammadbeigi A. The four-dimensional ultrasonography effects on changes of foetal and maternal heart rate: Are these interventions safe?. Adv Hum Biol 2018;8:155-8

How to cite this URL:
Naafe M, Saafi F, Larijani HH, Jamilian M, Sadeghi B, Mohammadbeigi A. The four-dimensional ultrasonography effects on changes of foetal and maternal heart rate: Are these interventions safe?. Adv Hum Biol [serial online] 2018 [cited 2020 Dec 2];8:155-8. Available from: https://www.aihbonline.com/text.asp?2018/8/3/155/241927

  Introduction Top

Foetal ultrasound imaging is widely used in the world. Ultrasonography is one of the prenatal diagnostic methods that used to detect any genetic diseases, defects, and anomalies. In addition, this method could determine the foetal health, growth, and age as well as the prediction of the exact time of delivery.[1],[2] Today, the three-dimensional (3D) and 4D ultrasound imaging has turned into one of the main tools to assess the foetal abnormalities.[3] In fact, the 3D ultrasound is the reconstructed version of the 2D imaging, obtained through sweeping the required areas by ultrasound waves.[1],[3]

Post-imaging reconstruction leads to the detection of a wide range of impairments, especially those, which engage face, skeleton, and limbs.[4],[5] A live 3D imaging is called a 4D ultrasound.[6] Although the epidemiological studies have failed to reveal the harmful effects of the ultrasonography on human beings, the ultrasound is as an energy source that has the potential to create some specific biological effects.[7],[8]

The mechanisms by which the ultrasound can affect the tissues are mainly divided into two broad thermal and non-thermal categories.[9] Acoustic effects are known as non-thermal mechanisms, which can generate biological effects without creating a high temperature. The results of these mechanisms are generally known as 'mechanical effects'.[10] The mechanical effects usually cause no changes in the foetus since they happen due to the presence of very small air bubbles, which are not found in foetal tissues.[9],[10] On the other hand, the acoustic effects, which apply their energy through increasing the temperature of the tissues to more than their physiological normal temperature, are recognized as the thermal mechanisms. Heat can change body tissues in many ways; accordingly, a rapid temperature raise caused by high-intensity focussed ultrasound can easily destroy anything in its hotspot. In lower temperatures, ultrasonic attenuation may cause induced hypothermia in the targeted area. The hypothermia creates because slowing 5%–7% in cellular metabolism due to 1°C dropping the body temperature.[11],[12] This kind of heat can also damage the biological systems by inducing other changes, such as increasing the metabolism and tissue perfusion.[13],[14] Hyperthermia can also lead to further detrimental effects, especially in tissues with low levels of perfusion.[12] This phenomenon is of paramount importance in the foetal tissues, specifically during the organogenesis (i.e., the first trimester) and cell migration (i.e., the second and third trimesters) periods.[15],[16] With this background, the present study aimed to evaluate the changes in foetal heart rate (FHR) and maternal heart rate due to 4D ultrasonography immediately after ultrasound imaging.

  Materials and Methods Top

This descriptive study was conducted on 178 pregnant women, who were referred to the ultrasound clinic for undergoing a 4D ultrasonography. The minimum sample size was calculated 130. It was estimated based on Type I error equal 0.05, power 80% and the minimum difference for two mean 0.04 and standard deviation for means equal 0.1. All the individuals signed the informed consent form for participation in the study. Moreover, the Ethical Committee of Arak University of Medical Sciences approved the protocol of this study by 92-151-11 code.

An experienced expert using the Medison 8000 Live Ultrasound Machine performed all ultrasound scans. After filling out the demographic forms, the baseline FHR was measured in the participants at the beginning of the 2D ultrasound imaging. At the same time, the maternal heart rate was recorded for a minute. Afterwards, the 4D ultrasonography was conducted, and all these parameters were documented at the end of the combined ultrasound imaging.

Inclusion criteria were women with 18–45 years old, having 4D sonography request and gestational age between 15 and 35 weeks. The exclusion criteria were any foetal defects or anomalies, fever in mother, history of cardiovascular diseases and arrhythmia, drug abuse or consumption of any medication that could affect the participant's heart rate and temperature of mothers.

Data analysis was performed using descriptive statistics including mean, standard deviation, and error bar for description data. Moreover, paired t-test and Pearson's correlation coefficient were used for inferential analysis. Analysis of covariance (ANCOVA) was used to adjust the effect of baseline heart rate in foetus and mother as well as the sonography effect. All the analysis conducted by IBM SPSS Statistics for Windows, Version 20.0 (IBM Corp. 2011. Armonk, NY, USA). P < 0.05 was considered statistically significant.

  Results Top

In total, 178 pregnant women were evaluated through ultrasound imaging. The mean age of the participants was 29.34 ± 5.02, which had a normal pattern and ranged from 18 to 45. The clinical and demographic characteristics of the participants are provided in [Table 1]. Furthermore, the mean gestational age was 19.92 ± 2.95 weeks. In addition, the mean duration of 2D and 4D ultrasound imaging was 1249.8 ± 257 s, the minimum and maximum of which were 840 and 2280 s, respectively. Moreover, mean 4D ultrasound duration was 246.1 ± 83.3 with a range of 65–481 s.
Table 1: Clinical characteristics of the participants including mean and standard deviation of age, gestational age of participated mothers and duration of sonography

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The changes in FHR and mother heart rate before and after the ultrasound imaging are presented in [Table 2]. The results of the paired t-test demonstrated no significant difference between the FHRs before and following the ultrasound imaging (P = 0.394) [Figure 1]a. Moreover, the maternal heart rates were estimated before and after performing the 4D ultrasonography, and the mean of maternal heart rates was 93.21 ± 12.27 and 90.69 ± 9.83 before and after the 4D ultrasound imaging, respectively. Furthermore, the paired t-test revealed a significant difference between the maternal heart rates before and following the ultrasound imaging (P < 0.001) [Figure 1]b. However, a significant decrease was showed in heart rate after sonography in mothers who were under study.
Table 2: Comparing the mean and standard deviation of mother and foetal heart rate before and after sonography

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Figure 1: Foetal (a) and maternal heart rate (b) before and after the multidimensional ultrasonography.

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Moreover, there was a direct correlation between the mean of changes in FHR and sonography duration (r = 0.368, P ≤ 0.001). To adjust the effect of sonography duration, ANCOVA was used as a multivariate model. The ANCOVA showed [Table 3] that base FHR (β = 0.659, 95% confidence interval [CI]: 0.482–0.836, P < 0.001) was only related factor for change in FHR, while the sonography was not related factors (β = 0.006, 95% CI: 0.011–0.024, P = 0.467). Moreover, the effect of sonography on Mother heart rate (MHR) was not significant (β = 0.005, 95% CI: 0.014–0.024, P = 0.570), while the base MHR was associated directly with MHR change (β = 0.604, 95% CI: 0.494–0.714, P < 0.001).
Table 3: Analysis of covariance results after adjusting the confounding effects of base foetal and mother heart rate

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  Discussion Top

Today, ultrasound, which is known as a safe imaging technique, is widely used in medicine and midwifery. Nevertheless, the thermal and non-thermal mechanisms are recognized as potential biological effects of exposure to ultrasound, and the majority of studies have confirmed the safety of this method. However, most of these studies were conducted on old ultrasound machines, and the safety of modern devices has not been approved yet. However, we showed that the 4D ultrasonography is a safe method and did not effect on fetal heart, while a decreasing effect was observed in maternal heart rate and it need to future studies.

According to the results of the present study, application of a 4D ultrasound device had no significant impact on the FHR, which is an indicator of increased body temperature in foetus. However, a significant decrease was observed in the maternal heart rate following the ultrasound imaging. The foetal heartbeat begins at 6 weeks of gestation, which results in the formation of embryonic circulatory system. Placenta is almost completely formed by the 11 weeks of gestation, and the elementary components of the perfusion blood flow get in their position.[2],[17] It should be considered that during the ultrasound imaging in the first few months, the embryo's heat dissipation mechanism is through distribution and not perfusion.[3],[18]

The acoustic effects of a diagnostic ultrasound imaging cause an increase in the temperature of the foetal tissue.[12],[19] When ultrasonography is performed on the bone, most of the energy will be converted into heat.[9],[13] Accordingly, the temperature approximately bones will increase alongside with bone development during pregnancy.[12],[19] Although adverse fetal outcomes may happen at any period of the pregnancy, especially by affecting to chronic disease such as diabetes.[20],[21] Adverse foetal outcomes have been demonstrated in an animal research that the most severe thermal effects occur during the organogenesis.[13],[19]

Some studies examined the impact of the ultrasound foetal exposure on growth, physiologic and haemodynamic variables such as heart rate and temperature.[17],[18],[22] Horder et al. study showed that 120-s exposures with ultrasound increased the mean temperature of the sphenoid bone to 1.5°C. This increase was easily distributed to the adjacent hypothalamic tissue, which is responsible for adjusting the body temperature through changing the heart rate.[23] However, it was demonstrated in the mentioned study that the exposure to ultrasound imaging led to no significant change in the FHR.

In 2009, the World Health Organization conducted a review study to evaluate 41 studies on the safety of ultrasound during pregnancy. According to the results of this review, ultrasound was not associated with such foetal and maternal complications as development of physical or neurological impairment, increased risk of malignancy in childhood, weak mental function and mental diseases.[18]

The current study has some limitations. However, we showed that ultrasound imaging has a reduction effect on mother heart rate, while this change is not clinically important and the authors suggested that used these results with attention. Moreover, the long-time prospective side effects of ultrasound imaging need to more studies, and we cannot assess them.

  Conclusion Top

In the current study, the maternal heart rates decreased after performing the ultrasound imaging, which might be due to the maternal stress reduction owing to leaving the waiting room or lying down, hearing the FHR and getting assured about the health of the neonate. According to the findings of the present study and those of the literature, it seems that the diagnostic ultrasound imaging is a safe method for foetus. It is recommended that long-term studies should be conducted in the future to assess the association of the 4D ultrasound imaging with the preterm labour, post-partum complications and mental problems.


This study is the result of a project approved by the Research Deputy of Arak University of Medical Sciences, Arak, Iran. Hereby, we extend our gratitude to the Deputy of Research, Research Committee, for their cooperation in this study.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

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Paladini D, Volpe P. Ultrasound of Congenital Fetal Anomalies: Differential Diagnosis and Prognostic Indicators. London: CRC Press; 2014.  Back to cited text no. 2
Zheng Y, Zhou XD, Zhu YL, Wang XL, Qian YQ, Lei XY, et al. Three- and 4-dimensional ultrasonography in the prenatal evaluation of fetal anomalies associated with trisomy 18. J Ultrasound Med 2008;27:1041-51.  Back to cited text no. 3
Bermejo C, Martínez Ten P, Cantarero R, Diaz D, Pérez Pedregosa J, Barrón E, et al. Three-dimensional ultrasound in the diagnosis of müllerian duct anomalies and concordance with magnetic resonance imaging. Ultrasound Obstet Gynecol 2010;35:593-601.  Back to cited text no. 4
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Sheiner E, Hackmon R, Shoham-Vardi I, Pombar X, Hussey MJ, Strassner HT, et al. A comparison between acoustic output indices in 2D and 3D/4D ultrasound in obstetrics. Ultrasound Obstet Gynecol 2007;29:326-8.  Back to cited text no. 7
Shipp TD, Levine D, Barss V. Basic Principles and Safety of Diagnostic Ultrasound in Obstetrics and Gynecology. UpToDate Literature Review; April, 2016.  Back to cited text no. 8
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Zhou J, Poloyac SM. The effect of therapeutic hypothermia on drug metabolism and response: Cellular mechanisms to organ function. Expert Opin Drug Metab Toxicol 2011;7:803-16.  Back to cited text no. 11
King RL, Liu Y, Harris GR. Quantification of temperature rise within the lens of the porcine eye caused by ultrasound insonation. Ultrasound Med Biol 2017;43:476-81.  Back to cited text no. 12
Duck FA. Hazards, risks and safety of diagnostic ultrasound. Med Eng Phys 2008;30:1338-48.  Back to cited text no. 13
Houston LE, Odibo AO, Macones GA. The safety of obstetrical ultrasound: A review. Prenat Diagn 2009;29:1204-12.  Back to cited text no. 14
Cruz-Lemini M, Valenzuela-Alcaraz B, Figueras F, Sitges M, Gómez O, Martínez JM, et al. Comparison of two different ultrasound systems for the evaluation of tissue Doppler velocities in fetuses. Fetal Diagn Ther 2016;40:35-40.  Back to cited text no. 15
Tonni G, Grisolia G, Sepulveda W. Second trimester fetal neurosonography: Reconstructing cerebral midline anatomy and anomalies using a novel three-dimensional ultrasound technique. Prenat Diagn 2014;34:75-83.  Back to cited text no. 16
Salomon LJ, Alfirevic Z, Berghella V, Bilardo C, Hernandez-Andrade E, Johnsen SL, et al. Practice guidelines for performance of the routine mid-trimester fetal ultrasound scan. Ultrasound Obstet Gynecol 2011;37:116-26.  Back to cited text no. 17
Torloni MR, Vedmedovska N, Merialdi M, Betrán AP, Allen T, González R, et al. Safety of ultrasonography in pregnancy: WHO systematic review of the literature and meta-analysis. Ultrasound Obstet Gynecol 2009;33:599-608.  Back to cited text no. 18
Abramowicz JS, Barnett SB, Duck FA, Edmonds PD, Hynynen KH, Ziskin MC, et al. Fetal thermal effects of diagnostic ultrasound. J Ultrasound Med 2008;27:541-59.  Back to cited text no. 19
Tabatabaee HR, Mohammad-Beigi A, Yazdani M, Zaghami B, Mohammad-Salehi N. Gestational diabetes risk factors modeling in pregnant women. Int J Diabetes Dev Ctries 2007;27:11-3.  Back to cited text no. 20
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  [Figure 1]

  [Table 1], [Table 2], [Table 3]


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