During pregnancy a smoking mother increases the risk of her baby being born prematurely and of low birth weight. This is because the carbon monoxide in tobacco smoke binds with the haemoglobin (a protein in red blood cells) reducing the oxygen carrying capacity of the blood entering the placenta3.
Premature babies are at greater risk of suffering from growth and mental retardation, cerebral palsy and even death. Smoking also increases the possibility of complications developing during delivery such as excessive bleeding and fetal distress necessitating a caesarean delivery.
Breast milk deteriorates
When breastfeeding nicotine and cotinine are transferred into the breast milk of a smoking mother within six to seven hours after smoking.
The nutritional effects of this include:
- Reduced breast milk production and infant weight gain.
- Lower breast milk levels of antioxidants vitamins C and E.
- Lower fat levels in milk, important for growth and mental development.
- Lower iodine levels important for mental development.
- Higher cadmium resulting in lower levels of metallothionein. This is important for the metabolism of copper and zinc that aid height growth.
- Higher levels for orotic acid which may affect DNA synthesis and liver function
Despite these factors when smoking mothers choose to breast feed they offer their infants more protection against respiratory illness and decrease academic performance compared to bottle feeding.
Studies of smoking mothers have found that they are more likely to wean their babies earlier than non-smokers. This can increase the risk of childhood obesity.
Studies have found that the prevalence of colic was two times higher among infants of smoking mothers, but this was less if those infants were exclusively breastfed.
Effects on bone health
Smoking increases the requirements for vitamin C by 50 per cent. It also deletes iron, B group vitamins and antioxidants. The function of antioxidants is to prevent free radical damage to cells and organs. Nicotine and free radicals affect bone health in the following ways:
- Hormone balance affecting bone status is upset. The hormone cortisol increases, leading to bone breakdown while the hormone Calcitonin declines, slowing bone growth.
- Nicotine kills the osteoblasts that make bone cells.
- Smoking damages the blood vessels slowing the supply of oxygen in the blood. This means that fractures are slower to heal and the nerves to the toes and feet can be damaged increasing the likelihood of falls.
Weight control issues
Nicotine increases resting metabolic rate and is an appetite suppressant. It is estimated that smoking may increase energy expenditure by as much as 10 per cent over a day, which equates to around 200 calories. When people give up smoking they often gain weight as their metabolic rate returns to normal and appetite increases. Dietitians can help people who are trying to quit without weight gain.
Second hand smoke and young children
There are at least 250 chemicals in second-hand smoke that are known to cause cancer. The toxins from cigarettes are more highly concentrated in side stream smoke (the smoke released from the burning end of a cigarette) than mainstream smoke (the smoke breathed out from the smoker).
The smaller lungs and lighter weight of young children increases their vulnerability to the harmful effects of second-hand smoke. Breathing in smoke produced by others is known as "passive smoking". In young children this can increase the risk of:
- Middle-ear infections (including glue ear)
- Lower respiratory illnesses (including croup, bronchitis and pneumonia) particularly in children 0 - 2 years.
- The onset of asthma and worsening of asthmatic symptoms up to the age of 15 years but the effects are greatest in pre-school children. This may be due to impairment of airway growth during utero and postnatally as a result of irritation of their airways.
- Reduced lung growth.
- Sudden infant death syndrome (SIDS, or cot death).
Recommendations to reduce the detrimental effects of smoking on children
- Women should stop smoking before having children.
- If breastfeeding women want to give up then nicotine patches can help so discuss this with your doctor.
- If quitting is not possible then mothers should prolong the time between the last cigarette smoked and breastfeeding to minimise the exposure, switch to nicotine patches, smoke outside the house and avoid smoky environments.
- Breastfeeding is recommended over bottle feeding for infants with mothers who smoke.
- Smoking drains the body of many essential vitamins and minerals particularly those such as Vitamins C and E with antioxidant properties. Respiratory function can be improved when children are fed fresh fruit and vegetables each day and have a regular consumption of fish.
- No amount of supplementation with Vitamin C or antioxidants will make up for the damage of smoking. The only real solution is to quit smoking.
Lea Stening is one of New Zealand’s leading paediatric dietitians and has specialised in paediatric nutrition for 31 years. If you want more information about the nutritional impact of smoking contact her.
If you want to quit smoking visit Quitline or ring Quitline on 0800 778 778.
- Essential Mums