The World Health Organisation (WHO) today marks World No Tobacco Day. In 2019, smoking is still a major public health concern. Its effects on the consumer have been long known but are offspring of smoking mothers really at risk?

Smoking is a leading preventable cause of multiple health problems. It is estimated that 16 per cent of all deaths in England in 2015 were directly attributable to smoking, and that annually seven million deaths are related to smoking. The clinical and public health implications of smoking are extensive. It constitutes a strong independent risk factor for circulatory diseases, primarily myocardial infarction, stroke and vascular disease, as well as diseases of the respiratory system such as chronic obstructive pulmonary disease and various cancers. Yet despite the morbidity and mortality associated with smoking, it remains a highly prevalent practice in many countries.

The estimated prevalence of smoking during pregnancy in Malta stands at around 4.3 per cent.

Many studies have shown that smoking during pregnancy is the single most important avoidable cause of adverse pregnancy outcomes, resulting in severe short- and long-term negative effects for the mother and the unborn child. In this respect, smoking can be considered as the first major environmental risk factor encountered by the unborn foetus.

A cigarette contains around 600 chemicals that when burnt create over 7,000 compounds. When a pregnant mother smokes, these chemicals dissolve in her bloodstream, which is the baby’s only source of oxygen and nutrients. None of these compounds benefit the foetus; however, the most harmful are nicotine and carbon monoxide (CO), which can be transported across the placental membranes causing direct noxious effects. CO decreases oxygen delivery to the foetus and nicotine causes cardiovascular and central nervous system complications. Additionally, the many other dangerous by-products of combustion inflict significant damage to the foetus, in ways that are not fully understood.

The estimated prevalence of smoking during pregnancy in Malta stands at around 4.3 per cent

Importantly, the long-term negative consequences of in-utero exposure to smoking are permanent, and thus the complete cessation of smoking in pregnancy is strongly advocated. I will outline some of the adverse smoking-related complications of pregnancy.

• For women of childbearing age, active and passive smoking is linked to reduced fertility. Additionally, smoking during pregnancy is associated with significantly increased risk of obstetric complications, including premature rupture of membranes, chorioamnionitis, premature delivery, placental abruption and pregnancy-induced hypertension.

• Smoking during pregnancy is associated with an increased risk of miscarriage, stillbirth and congenital malformations. Some studies have shown that the offspring of smoking mothers  have a  20 to 70 per cent higher risk of severe congenital heart defects compared to offspring of non-smoking mothers.

• One of the most significant negative effects of smoking during pregnancy is intrauterine growth restriction. Multiple studies have shown that smoking mothers give birth to offspring who have significantly lower foetal birth weight, birth length and head circumference.

• Smoking during pregnancy has been linked to a decrease in pulmonary function in the offspring later in life, increased paediatric hospitalisation and mortality because of respiratory infections and an increased risk of wheezing and asthma in the child.

• Maternal smoking during pregnancy promotes increased body mass index (BMI) in children and augments the risk for obesity in childhood and adult life.

• Maternal smoking during pregnancy has been linked to growth restriction and decrease in the size of the foetal brain. The density of important parts of the foetal brain is diminished, and studies have demonstrated a decrease in coordination within the different parts of the foetal brain during processing of information and a deceleration in the ability to adequately respond to external stimuli in foetuses exposed to in-utero smoking. Offspring show higher rates of poor cognitive and behavioural outcomes including ADHD (attention deficit hyperactivity disorder), impaired learning, memory and cognitive dysfunction and a lowered IQ.

• Maternal smoking during pregnancy is associated with a 1.83-fold increased risk of in-hospital treated fractures at pre-school age. The fracture risk in childhood is perhaps increased as a result of modified bone development of the foetus.

The way forward

The continued popularity of tobacco smoking appears to defy rational explanation. Smokers, especially smoking mothers, mostly acknowledge the harm they are doing to themselves and their child – yet they continue to smoke. The reason is that nicotine generates strong urges to smoke that undermine concerns and overwhelm willpower. As explained in this article, tobacco smoking is classified as a main cause of miscarriage and underdevelopment of foetus.

However, this is preventable if cessation occurs early in pregnancy and the risk is mitigated by stopping at any time in pregnancy. A study by Butler et al (2004) also suggests that eating more fruit and soy fibre as an adult seems to be protective against some of the negative health effects often associated with early tobacco exposure. Contrary to common belief, Shahab (2009) concludes that those who stop smoking report higher levels of happiness and life satisfaction than those who continue.

Nonetheless, the natural answer is to never start smoking and make World No Tobacco Day every day.