Smart scales estimate body composition, including body fat and muscle mass, using Bioelectrical Impedance Analysis (BIA). Given the significant physiological changes during pregnancy, many individuals wonder if using these devices is safe for them and their developing baby. The primary concern revolves around the low-level electrical current used by the BIA technology, which necessitates understanding how these scales function and what precautions are advised by healthcare professionals and manufacturers.
How Smart Scales Measure Body Composition
Smart scales employ Bioelectrical Impedance Analysis (BIA) to estimate body fat, muscle, and water content. The scale sends a small electrical current through the body, typically from one foot pad to the other. Water and muscle tissue are excellent conductors because of their high water content, while fat tissue offers greater resistance.
The scale measures this resistance, or impedance, as the current travels. This measured impedance is then entered into a mathematical formula, along with inputs like height, age, and sex, to calculate the estimated body composition figures.
Safety Concerns Regarding Bioelectrical Impedance Analysis
The main safety concern centers on the minute electrical current generated by the BIA process. These currents are very low voltage, often around 70 microamperes. However, the developing fetus represents a highly sensitive physiological system, and research on the effects of minimal electrical exposure is limited.
Due to this lack of conclusive safety data, most smart scale manufacturers and medical experts advise against using the BIA function while pregnant. This recommendation acts as a precautionary measure, especially during the first trimester when rapid organ development occurs. The risk is that the current could potentially interfere with the developing fetus.
Accuracy of Readings During Gestation
Even if a smart scale were safe, the body composition readings would be highly unreliable during pregnancy. BIA technology relies on stable hydration levels for accurate measurements, but pregnancy involves significant shifts in total body water.
A pregnant person experiences an increase in blood volume, amniotic fluid, and overall fluid retention, especially in later gestation. The scale interprets this excess fluid as a change in lean mass, producing skewed estimates for body fat percentage and muscle mass. Relying on these inaccurate metrics can lead to confusion or inappropriate dietary decisions, invalidating the primary purpose of using the scale.
Recommended Practices for Tracking Weight
For tracking weight during pregnancy, use a standard, non-smart scale that measures only total body weight. Monitoring the overall weight gain trajectory is the most important metric for both the healthcare provider and the individual. The goal is to ensure weight gain falls within the healthy ranges recommended by medical guidelines, which are based on pre-pregnancy Body Mass Index (BMI).
It is helpful to weigh at the same time of day, wearing similar light clothing, and using the same scale for consistency. Regular communication with a healthcare provider remains the most reliable way to monitor weight gain goals and ensure a healthy pregnancy.