A non-invasive way to detect pregnancy complications

Scientists have developed a near infrared technology to non-invasively detect common pregnancy complications.

The rate of overall pregnancy and childbirth complications in adult women in the US rose between 2014 and 2018 (1). This rise may be explained by the increase in women with pre-existing conditions before pregnancy and advanced maternal age (6).

The most common pregnancy complications include high blood pressure, gestational diabetes, infections, preeclampsia, preterm labor, depression & anxiety, miscarriage, and stillbirth (7).

The placenta’s role in pregnancy complications

Often, problems with the placenta are the root cause of many of pregnancy complications. Scientists have theorized placental problems can lead to long-term diseases in adults such as cardiovascular disease, diabetes, and obesity (5).

The placenta is a complex organ that is responsible for multiple functions throughout pregnancy (2). It grows in the uterus and is delivered after birth (3). The primary job of the placenta is to send oxygen and nutrients to the fetus and remove waste products (4).

Because of possible complications to mother and child, it is difficult for doctors to study the placenta.

Most studies are performed after birth or on animals. Ultrasound imaging technology is the most common non-invasive tool used to study the placenta during pregnancy.

Ultrasound is useful for determining the size and location of the placenta, as well as any placental damage or blood flow problems between the placenta and fetus. Unfortunately, ultrasound cannot give specific information on placental oxygenation, which is critical to baby’s health (5). Other non-invasive methods to assess placental oxygenation are available but are not cost-effective nor easily portable.

A solution to assess the placenta non-invasively

Scientists from the National Institutes of Health proposed near-infrared spectroscopy (NIRS) as a possible noninvasive diagnostic tool for placental oxygenation. They developed a prototype device using NIRS to monitor placental oxygenation levels. Their results were published in the journal Biomedical Optics Express.

The NIRS device prototype was created from flexible material so it could be placed across the skin. The device contained six LED lights and two photodiodes, which convert the light signal into electric current. It was designed to be able to detect light at low intensity. Data from the device was transmitted wirelessly to a computer or cell phone.

One of the challenges in building and using an NIRS device to measure placental oxygenation is the location of the placenta. Usually, the placenta attaches to the front or back wall of the uterus (8). Because the distance the light will travel is based on the thickness of the layers, the NIRS device could only be used to measure the oxygen level of placentas attached to the front, known as anterior placentas.

Testing the new device

After building the prototype, the scientists tested the device in several situations designed to simulate different combinations of skin color and thickness. Additionally, the prototype was tested on two human subjects at various positions on the body. Data obtained from the device was mathematically analyzed to calculate the oxygen levels. Each oxygen measurement was taken in triplicate and compared to each other to determine the device’s accuracy.

Using the NIRS to measure blood oxygen levels

After the NIRS device was validated, a small study was conducted of 12 pregnant women. Blood oxygen levels were measured using a pulse oximeter and an ultrasound machine. Skin, fat, and uterine tissue thickness was also measured on the upper, middle, and lower parts of the placenta (5).

The NIRS device was placed in the same position on the abdomens for thirty seconds. Measurements were continuously taken during the thirty seconds, resulting in fifteen data points, which were averaged.

Participants were placed into two groups based on their medical history: complicated pregnancy and uncomplicated pregnancy. The scientists mathematically processed the data to determine how the NIRS device oxygen measurements compared to the traditional measurements and whether oxygen levels in each group increased pregnancy risks.

The NIRS device was determined to give accurate results for measuring oxygen levels in anterior placentas. The uncomplicated pregnancy group had higher oxygen levels than the complicated pregnancy group. Also, patients with placental lesions had significantly lower oxygen levels than those without lesions.

The study authors are hopeful the NIRS device can be used to measure placental oxygen levels. Due to the study’s small sample size, additional study with a larger group is recommended.

References:

1. Overall pregnancy and childbirth complication rates U.S. 2014-2018. Statista. Accessed June 21, 2021. https://www.statista.com/statistics/1142836/overall-pregnancy-and-childbirth-complication-rates-us/
2. Burton GJ, Jauniaux E. What is the placenta? American Journal of Obstetrics and Gynecology. 2015;213(4, Supplement):S6.e1-S6.e4. doi:10.1016/j.ajog.2015.07.050
3. BD Editors. Placenta. Biology Dictionary. Published July 26, 2017. Accessed June 21, 2021. https://biologydictionary.net/placenta/
4. Gude NM, Roberts CT, Kalionis B, King RG. Growth and function of the normal human placenta. Thrombosis Research. 2004;114(5-6):397-407. doi:10.1016/j.thromres.2004.06.038
5. Nguyen T, Khaksari K, Khare SM, et al. Non-invasive transabdominal measurement of placental oxygenation: a step toward continuous monitoring. Biomedical Optics Express. 2021;12(7):4119. doi:10.1364/boe.424969
6. Norton A. Serious Birth Complications Rising In The U.S. HuffPost. Published October 24, 2012. Accessed June 21, 2021. https://www.huffpost.com/entry/us-birth-complications_n_2008771
7. What are some common complications of pregnancy? http://www.nichd.nih.gov/. Published January 31, 2017. Accessed June 21, 2021. https://www.nichd.nih.gov/health/topics/pregnancy/conditioninfo/complications
8. Fadl S, Moshiri M, Fligner CL, Katz DS, Dighe M. Placental Imaging: Normal Appearance with Review of Pathologic Findings. RadioGraphics. 2017;37(3):979-998. doi:10.1148/rg.2017160155
9. Image by Pexels from Pixabay