Noise pollution is a hazard when it is present in the environment, and it is associated with many health impacts in adults. Recent research has also shown that noise pollution can be harmful to a pregnant woman as it has negative effects on the unborn baby. The children who are born to women who expose themselves to high sounds have been reported to have an increased risk of having hearing problems. This noise can be measured as 85 decibels, or it can also be higher.
Developmental stages of hearing in the fetus
The sensory end organs located in the peripheral region together with the human cochlea complete their development by 24 weeks of the pregnancy. Sounds when the pregnancy is at 30 weeks, the ear of the baby is mature enough and can respond to sounds that filter in the body. However, the sounds are muffled as they cannot be amplified like in adults where this function is done by the middle ear and the ear drum. Therefore, the sounds that are too loud for the mother might not be the same for the baby but this is only true when they are not too loud or for too long.
When the pregnant woman undergoes an ultrasound, startle responses and blinking can be observed at 24-25 weeks, and this are consistently observed at 28 weeks. This is an indication of the maturation of the auditory system and its connection to the central nervous system. The threshold of hearing for a fetus that is 27-29 weeks gestation is 40dB, and this decreases with increased gestation period. The threshold is reduced to almost the same as that of an adult i.e. 13.5 dB, and this indicates that the postnatal maturation of the pathways is continuous. This report indicates that the exposure of the fetus to noise pollution occurs when the hearing system is undergoing normal development and maturity. The sound is transmitted well to the uterus of a pregnant woman and therefore it can have an impact on the baby. The impact of the noise on the unborn baby is one of the things that are used to show the well being of the fetus in terms of development and maturity.
The effects of noise pollution to the fetus
Studies have shown that children who are born to women who have been exposed to high-frequency noise are likely to develop hearing loss at later stages of their lives. This is common with women who are exposed to a noise ranging from 85-95 dB at their place of work while pregnant.
The studies that were done on animals showed that there is increased sensitivity to noise as the cochlear develops, and this can cause impairment to hearing, but the same has not been confirmed in human beings.
A study that was done by the Chinese showed that the woman who was exposed to noise pollution during the first trimester of pregnancy were linked to congenital abnormalities in their unborn babies. These are the abnormalities that are listed in ‘The international classification of diseases, ninth revision’. These abnormalities involve chromosomes, and they are likely to cause birth defects.
Another study showed that the placental lactogen in women who were exposed to noise was lower than in those who lived in quiet areas.
The inner, middle and outer parts of the ear of a fetus are developed after 24 weeks of pregnancy, and the sound can be transmitted t the brain of the unborn child for transmission. This report was given by the senior obstetrician and consultant gynecologist at a hospital based in Gurgaon, Pooja Mehta. The consultant also reported that exposure to noise above 90-100 dB can increase the risk of developing hearing loss in the unborn baby.
When an individual is regularly exposed to noise pollution above 85 dB, it can lead to damage in the hearing system.
When a pregnant woman is exposed to extremely high sounds, then other aspects of health can also be affected, and this includes having a reduced birth weight or premature birth.
Another gynecologist who works at Fortis, Vimal Grover reported that women who are exposed to high-intensity noise when pregnant are likely to have preterm deliveries. They may also have a disruption in the normal development and growth of the premature infant, and this may cause health issues.
When noise is an occupation hazard for the mother, then it can be harmful to the baby. This is seen in cases where the pregnant woman is exposed to high-intensity noise and for long hours regularly. Noise pollution can cause premature labor and delivery, abnormal development in the unborn child causing disabilities. It can also cause hearing impairment in the later stages of the child’s development.