How Infants Are Affected By Prenatal Nicotine Exposure

The most delicate and important periods in a child’s life are the periods of development from conception to birth. Therefore, it is important for parents to avoid and protect against teratogens as they can cause birth complications and increase the risk of prenatal abnormalities. Cigarette smoke is one of the most common teratogens exposed during pregnancy. There are approximately 4, 000 chemicals in cigarette smoke including two toxins that work together to narrow the mother’s blood vessels: nicotine, and carbon monoxide. The tightening of the umbilical cord greatly reduces the baby’s oxygen and nutrient supply which can cause stillbirth, low birth weight, and premature delivery. Many studies show that this effect can have lifelong effects on the baby’s brain, increasing the risk of learning disorders, behavioral problems and lower IQs. However, existing studies fail to separate MSDP effects from other genetic and environmental factors and fail to examine the effects of secondhand smoke (SHS).

The carefully designed study, “Effects of Prenatal Nicotine Exposure on infant language development: a cohort follow up study, ” by Martínez, Moreso, Serra, Val, Macías, and Sans (2016), considers other confounding factors and builds upon existing knowledge to demonstrate the long-term effects of prenatal nicotine exposure on cognitive development. This study provides data examining the effect of both MSDP and SHS on infant cognitive development at 6, 12, and 30 months old. More specifically, the data shows the impact MSDP and SHS have on infant cognitive and language development. Unlike many other related studies, “Effects of Prenatal Nicotine Exposure on infant language development: a cohort follow up study, ” took into account a group of prenatal secondhand exposed infants, a consideration that is often missing in related studies. The study also considers prenatal and postnatal variables including the following factors: prenatal maternal anxiety, neonatal birth weight, gestational age at birth, parity, postnatal exposure to tobacco smoke, infant breastfeeding, family socioeconomic status (SES), parents’ general psychopathology and mother–infant attachment.

The study followed 158 mothers during pregnancy and their infants at 6, 12 and 30 months old. The mothers answered survey questions asking about their smoking habits during each trimester and during the infant’s first 30 months; mothers who did not smoke but smelt cigarette smoke at home or work regularly were included in the secondhand smoke category. The Bayley Scales of Infant Development tested the babies’ cognitive development at 6, 12 and 30 months old. The study utilized Bayley’s mental, motor, and behavior rating scales to assess the infants. From these scales, each infant received a mental development index and a psychomotor development index. The infants’ language development was tested at 12 and 30 months.

To eliminate prenatal and postnatal variables that could affect the study’s outcome, the study only followed mothers who were “…over 18 years of age, at no more than 11 weeks of gestation, being healthy, with a singleton pregnancy, and having no chronic illness affecting nutritional status, such as diabetes type I, Crohn’s disease and celiac disease”. The infants were all born in the same hospital and could not be included in the study if the had any medical problems in the first week of life. In addition, the study assessed infant-mother attachment and maternal anxiety using the Parenting Stress Index and the Spanish version of the State-Trait Anxiety Inventory. The article explained that the participants agreed to share information about their socioeconomic status and their general health status. By obtaining this information, the study could attempt to consider the level of impact these factors had on the outcome. The study found that both types of smoke exposure are associated with poor cognitive development scores. Infants 6 months old that were prenatally exposed to smoke and SHS had lower language scores, had a more difficult time imitating words, and trouble producing prelinguistic vocalizations. The infants at 30 months old had lower receptive and expressive abilities. The overall findings were that both types of smoke exposure, MSDP and SHS, negatively affect health, cognitive and behavior outcomes. The researchers concluded that prenatal smoke exposure is a public health concern.

One of the study’s limitations was how they measured prenatal smoke exposure. Although the mothers were asked about the smoke exposure seven times and were guaranteed confidentiality, there is always risk of bias. In other words, total reliability cannot be guaranteed by survey results. Another potential limitation is that there are many factors that effect IQ and cognitive development. It is impossible to measure the precise level of impact each factor had on the study’s outcomes. Therefore, the conclusions can only suggest a strong correlation, not a direct tie. SES, parents’ academic level, and their type of job were considered. However, these factors, although good indicators, can’t determine the parents’ IQ. Even if they could, the infants’ IQs may be lower or higher due to many other contributing factors. Although the study took other factors into account, so many other things impact cognitive development. It wasn’t possible to capture all the factors in this study.

Even with these limitations, this study is a reliable source. The researchers did a good job of considering potential genetic and environmental factors. Their survey questions such as “Do you smoke?” avoid wording bias. Although some mothers may not have wanted to admit how much they continued smoking during pregnancy, they were less likely to change their answer due to the wording to the question. This study should be considered even with some of its unavoidable bias because of the clear association between MSDP and SHS exposure and impaired cognitive and language development. I think that this study brought more of the concerns prenatal smoke exposure into light. The study was designed in a way that avoids a lot of potential bias, making the conclusions drawn more valuable. It is a reliable study that acknowledges its own limitations and considers a multitude of potential factors. This study suggests a strong association between smoking habits and babies’ cognitive development. The study’s built in ethos could encourage pregnant woman to quit smoking or at least limit their infants smoke exposure. After reading about this study, it is evident to me that pregnant woman should try to quit smoking and to avoid secondhand smoke exposure to avoid dangerous complications and long-term effect on their baby’s cognitive development.