Study: Fetus synchronizes its biological clock with the mother's time before birth

 

Fetus synchronizes

Study: Fetus synchronizes its biological clock with the mother's time before birth

A recent study revealed that the regulation of a person's circadian rhythm begins at a very early stage of embryonic development before birth.
Living organisms, including humans, rely on an internal system known as the biological clock, which regulates the sleep-wake cycle, metabolism, and vital bodily functions according to the sequence of night and day, in a pattern known as circadian rhythms or the daily biological clock.

Researchers confirm that disruption of these rhythms, resulting from staying up late, irregular work, or sleep disturbances, may be linked to long-term health effects including metabolic and mood disorders.
The study, published in the journal Biological Rhythms and conducted by researchers from the University of Washington, focused on a fundamental scientific question: When does the biological clock start working inside the fetus, and how is it adjusted to local time?

The researchers explained that the mother acts as the "biological synchronizer" for the fetus during pregnancy, as time signals are transmitted through the placenta that help regulate the fetus's internal rhythm even before it is able to sense light.

How was the biological clock monitored inside the womb?

To monitor the biological clock inside the womb, the research team relied on an experimental model using genetically modified mice, in which a protein associated with regulating the biological clock was linked to a luminous protein similar to the substance responsible for the light of fireflies. When this protein was activated inside the embryos, a light glow appeared that could be tracked using highly sensitive cameras, allowing scientists to directly monitor biological rhythms inside the womb.

The results showed that the fetuses exhibited clear periodic patterns that gradually synchronized with the mother’s daily activity cycle, particularly during the later stages of pregnancy, equivalent to the last third of human pregnancy.

Signaling via the placenta and regulating biological timing

The researchers explained that the synchronization between the fetus's and mother's rhythms occurs even before the fetus is able to receive light, indicating the presence of biological signals transmitted through the placenta.
Scientists believe that glucocorticoid hormones, which regulate the body's response to stress and are themselves subject to a circadian rhythm, may play a key role in transmitting these time signals from mother to fetus.

Hormonal effects and potential medical implications

The results also showed that giving synthetic hormones similar to glucocorticoids during pregnancy may accelerate the adjustment of the biological clock in fetuses, which may have implications for medical practices related to the treatment of pregnancy complications or premature birth.

Researchers have also noted a link between the absence of rhythmic activity of the biological clock in fetuses and the occurrence of miscarriages, although it is not certain that this link is directly causal.

The study suggests that maintaining regular sleep and light exposure during pregnancy may be an important factor in supporting healthy fetal development, especially given that a large percentage of the world's population is exposed to artificial nighttime light, which may disrupt circadian rhythms.

The researchers conclude that understanding the timing of the start of the biological clock inside the womb may help identify "sensitive windows" during embryonic development, in which biological disruption can have a long-term impact, potentially opening the door to improved medical guidelines and health policies related to pregnancy and newborn health.