Research indicates that microplastics may pose significant risks to fetal development during pregnancy. A systematic review conducted in 2023 found evidence suggesting that these tiny plastic particles, measuring less than five millimeters, can cross from the mother’s bloodstream into the fetus. This potential transfer raises concerns about the health implications for developing babies and future generations.
The breakdown of plastic waste contributes to the emergence of microplastics. Over time, environmental conditions, sunlight, and mechanical wear reduce larger plastic items into smaller fragments, including macroplastics, mesoplastics, and ultimately nanoplastics, which measure less than 100 nanometers. These particles stem from everyday products such as polyethylene in plastic bags, polypropylene in food containers, and polystyrene in takeaway cups.
Research published in a 2025 review examined various studies involving animals, lab-grown cells, and human tissue samples, revealing that both microplastics and nanoplastics can potentially penetrate the placental barrier. Once these particles enter the placenta, they may disrupt the delicate functions of the fetoplacental unit—the combined system of placenta and fetus.
Studies indicate that microplastics could obstruct normal cell communication pathways, induce programmed cell death (apoptosis), and cause oxidative stress, a form of cellular damage. There are also concerns that certain plastics may interfere with the endocrine system, which regulates hormone release crucial for growth and development.
The ability of microplastics to bypass the placenta’s selective filtering capabilities has significant implications. Typically, the placenta protects the developing fetus from harmful substances while allowing essential nutrients and oxygen to pass through. If microplastics penetrate this barrier, they could interfere with organ formation and the long-term health of the fetus during a critical phase of human development.
While the exact mechanisms that allow these particles to cross into the placenta remain unclear, factors such as particle size, weight, and surface charge appear to influence this process. Laboratory experiments using human placental models show that larger polystyrene particles (50-500 nanometers) did not harm placental cells and, in some cases, seemed to enhance their survival. In contrast, smaller particles (20-40 nanometers) were associated with cell death and inhibited growth.
Animal studies have yielded mixed results regarding the extent to which nanoplastics reach the fetus. Some experiments indicated that most nanoplastics remained in the placenta, while others demonstrated that smaller particles could migrate into fetal organs, including the brain and lungs. Research has also linked smaller placentas and lower birth weights to potential health impacts, suggesting that certain nanoplastics may pose genuine risks during pregnancy.
The fetal development process is finely regulated, making it particularly sensitive to environmental disturbances during critical periods. According to the “developmental origins of health and disease” hypothesis proposed by Barker, harmful exposures during pregnancy can permanently alter the formation and function of organs. Inadequate nutrition, toxins, stress, and pollutants like microplastics may increase the risk of chronic conditions such as diabetes and heart disease later in life.
Microplastics can also disrupt the gut’s microbial balance, damage the intestinal lining, and affect nutrient absorption. Laboratory studies have shown that polystyrene nanoparticles can enter embryos and accumulate in organs, causing effects such as slowed heart rates even at low doses. When inhaled by the mother, these particles can travel to the placenta and subsequently to the fetal brain and heart.
Concerns extend to the developing brain, as some studies indicate that microplastics can accumulate in areas crucial for learning, memory, and behavior. Once in these regions, they may cause oxidative damage, alter neurotransmitter levels, and inhibit the expression of genes necessary for healthy brain development. Prenatal exposure to microplastics in animal models has been associated with anxiety-like behavior, learning impairments, and abnormal nerve cell growth.
Despite these alarming findings, significant knowledge gaps persist. Much of the current research relies on animal models or controlled laboratory settings, with limited direct evidence from pregnant women. The pathways through which microplastics travel in the body, the extent of accumulation in the placenta and fetus, and their clearance mechanisms remain poorly understood.
There is an urgent need for further research to determine whether microplastics genuinely threaten reproductive health and fetal development. Understanding these risks could influence policies related to plastic production, consumption, and disposal, as well as inform healthcare guidance for pregnant women.
According to Priya Bhide, Clinical Reader at the Women’s Health Research Unit at the Centre for Public Health and Policy, Queen Mary University of London, and Nelima Hossain, Academic Trainee in Public Health at the same institution, addressing the gaps in understanding the impact of microplastics on fetal health is critical for public health. This knowledge could lead to proactive measures that safeguard future generations from the potential harms of plastic pollution.
