Additionally, during the first months of the baby's life, the neurophysiologic bases for the infant's interactions with others are developing. The parts of the brain that are involved in relating and responding to social signals are being stimulated and developed daily. The infant's earliest social contacts can influence these neurochemical pathways, which mediate social interactions. This critical process will continue throughout infancy...[S]moking during pregnancy can impact infants by making them more excitable and irritable, less able to calm themselves down, and more needy of maternal touching and holding to remain relaxed.
Nicotine Makes Bonding More Difficult
A recently published paper in The Journals of Pediatrics (January, 2009) adds maternal smoking to the list of factors which influence this very early, very critical period and shows that smoking during pregnancy can impact infants by making them more excitable and irritable, less able to calm themselves down, and more needy of maternal touching and holding to remain relaxed. Among the many other factors known to interfere with the ability of a baby and a mother to respond to each other effectively enough to form a strong bond are prematurity, illness, neurologic problems, drug withdrawal, maternal depression, and substance use.
Maternal smoking during pregnancy is known to contribute to low birth weight, increased risk that a newborn will need intensive care unit treatment, increased risk for sudden infant death syndrome, and neurobehavioral problems later in life including attention deficit/hyperactivity disorder, conduct disorder, and conduct use. Yet 11-30% of pregnant women smoke, and in high-risk populations, the number rises to 50%. This is the first study to look at the impact of maternal smoking on infant behavior at such an early stage, the first 10-27 days.
The 56 infants in the study were all full term, healthy infants and there were no significant differences between their APGAR scores, birth weight, breast-feeding history, second hand smoke exposure or maternal depression. The mothers in the study were similar in socioeconomic status, did not use drugs or drink excessive alcohol, or have other confounding medical or social issues. Half smoked and half did not.
This study hoped to differentiate withdrawal from nicotine which occurs during the first five days after birth (and has different symptoms), from longer term effects of nicotine exposure on the developing nervous system by examining babies at 10 and 27 days of age, long after the withdrawal period had passed.
There were three objective tests used to measure infant behavior. The classic neurologic exam looks at muscle tone, reflexes, and functioning of the central nervous system. The neonatal behavioral assessment scale looks at a how a baby responds to the various states of arousal from lethargy to excitable, and how he acts as he changes from one stage to the other. It also assesses their ability to calm and relax themselves without needing an adult interaction such as talking, touching, or holding. The Finnegan scale is used to assess signs of drug withdrawal.
Maternal smoking behavior was measured by maternal report and by measuring cotinine in maternal saliva. Nicotine is metabolized into cotinine in the body and when a mother smokes 90% of her cotinine passes to her baby. Cotinine levels in baby's saliva was used to measure infant nicotine exposure from second hand smoke at home at the time of their neurodevelopmental evaluations on day 10 and day 27.
Irritability and Arousal Even After Withdrawal
The study demonstrated that when infants whose mothers had smoked, were examined at day 10 and 27 of life, they did not show classic withdrawal symptoms. However, they showed increased irritability and arousal, increased need for maternal intervention to calm them, more difficulty in responding to soothing, and fewer periods of quiet alert states. They demonstrated a profile of behaviors that potentially places more stress on mothers and leads to maternal exhaustion and feelings of failure, and creates potential barriers to effective mother-infant bonding. The researchers also postulated that the observed difficulties with behavioral regulation were potentially precursors of behavioral problems in the future.
The fact that these babies were full term, normal weight, healthy infants, unlike many babies who are exposed to maternal smoke in utero was especially concerning. It suggests even though their exposure to nicotine was not excessive enough to cause the other issues related to maternal smoking (such as low birth weight, small stature, increased risk of SIDS) they still had clear neurobehavioral changes. This raises worrisome questions about the impact of maternal smoking in babies who do show other complications of maternal smoking. It is possible that they would demonstrate more neurodevelopmental/behavioral problems than those seen in the healthy infants in this study.
Help for Mothers and Newborns
For women who smoke and who are pregnant or thinking about becoming pregnant, the study offers a clear picture of the types of bonding and other neurobehavioral problems their babies will likely face if they develop in the womb under the influence of nicotine. Pediatricians, obstetricians, family practitioners and midwives would do well to use this information in their efforts to influence their pregnant patients to stop smoking. Similarly, practitioners who are caring for infants whose mothers smoked through pregnancy are well advised to look for and ask specifically about the temperamental, irritable, stressful behaviors that were demonstrated in this study and provide interventions if needed.
Mothers can be taught how to react more effectively to challenging infants and thus to feel more successful. Infant behavior specialists can be consulted to intervene with particularly difficult mother-infant relationships. This study provides further evidence that pregnancy counseling and neonatal surveillance can provide key interventions to develop effective mother-infant relationships and to help neonates to realize their full developmental potential.
