Recent studies show that maternal melatonin and circadian rhythms directly influence fetal development. This can be seen in both the ovaries and the placenta, whereby the expectant mother produces melatonin. The placenta is particularly vulnerable to alternating episodes of hypoxia and reoxygenation.
Antepartum disorders, including pre-eclampsia, may be affected by chronodisruption, in other words unstable circadian rhythms. Disrupted melatonin cycles can have adverse future psychobehavioral problems in the unborn child. Additionally, disrupted melatonin cycles can affect the normal delivery of the fetus, since melatonin is known to work with oxytocin in a synergistic modality.
Differentiation in fetal sleep stages occurs within the third trimester. Researchers believe that sleep patterns during gestation can elucidate processes behind brain maturation as well as predict future behavioral patterns in children and adolescents. The patterns exhibited during the transition from quiet sleep to active sleep are statistically useful in supporting this hypothesis.
A recent study postulates that maternal obstructive sleep apnea may adversely affect fetal growth during the third trimester, and can even lead to stillbirth. However more studies, with respect to polysomnography, are needed to confirm this association.
Also during the late third trimester, fetal heart rate (FHR) is a key component in determining clinical outcomes of fetal delivery by either natural methods or surgical methods. When comparing FHR variability among quiet sleep and active sleep, one study showed that intrauterine growth restricted (IUGR) fetuses showed differences not seen in low-risk fetuses. These difference were observed in one of three measures studied during a 6-minute FHR window. IUGR fetuses showed decreased fetal movement as well as reduced response to external stimuli. These findings may signify a pathologic process that leads to fetal injury, which then manifests as a metabolic acidosis that subsequently depresses the fetal brain.
The mother-to-be can expect her dreams during the third trimester to focus on the upcoming childbirth. Scientists believe this may be due to the mother’s remodeling of maternal mental representations of her new role and the baby. Interestingly, the dream content tends to be frequently morbid later in pregnancy as the mother attends check ups more frequently and deals with a myriad of emotions ranging from excitement to anxiety.
Additional research shows that lack of proper sleep is an important contributor to post-partum blues. An expectant mother should be kindly reminded that she cannot do everything by herself and that keeping herself healthy is a good way to begin instilling good sleep hygiene in her baby.
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