Women receiving treatment for psychosis should be okay to keep taking their meds if they fall pregnant, according to a new study that followed hundreds of thousands of pregnant women through to birth, and their kids years into childhood.

It found women on antipsychotics are no more likely to give birth early or to underweight infants, than healthy pregnant women are. Additionally, no link was found between antipsychotic drugs in pregnancy and the development of attention deficit hyperactivity disorder ( ADHD) or autism spectrum disorder ( ASD) in the kids.

This should be reassuring for pregnant people who require antipsychotic medication for serious mental illness such as schizophrenia, as well as the doctors caring for these people; although there are still some health risks to understand.

"Our study results suggest that if pregnant women have a clinical need for antipsychotics, clinicians should not stop administering regular treatment because of a fear of birth outcomes with ADHD, ASD, preterm birth, and small for gestational age," write pharmaco-epidemiologist Zixuan Wang from the University College London and colleagues in their published paper.

But as the researchers note, birth outcomes and childhood developmental disorders could still be influenced by a mother's genetic factors – or the very conditions that need medical treatment – so let's take a look at what the study shows.

Firstly, it builds on past studies which yielded mixed results, leading to some uncertainty about whether antipsychotic medications are associated with some health risks for mothers and their children.

Earlier studies, which followed kids for a few years after birth, were not long enough to capture developmental disorders that tend to be diagnosed in later childhood, typically around 6 years of age for ADHD, Wang and colleagues say.

Antipsychotic drugs work by restoring the balance of brain chemicals and reduce symptoms such as disordered thinking, paranoia and hallucinations, which are characteristic of schizophrenia.

These types of drugs are also prescribed alongside other medications such as mood stabilizers for bipolar disorder. The use of newer, second-generation antipsychotics appears to be increasing among pregnant women and the general population, in numerous countries in recent years.

In this study, the researchers analyzed data from the medical records of hundreds of thousands of women who gave birth in Hong Kong over 15 years. Among these women, around 700 mothers had been on antipsychotic therapies during their pregnancies, and nearly 550 had children whose health outcomes were documented over at least 6 years.

"Our study found no evidence to support an association between antipsychotic medication use during pregnancy and an increased risk of neurodevelopmental disorders in children" such as ADHD or autism, Wang and colleagues write.

"Gestational exposure to antipsychotic drugs is [also] unlikely to pose a significant risk of preterm birth and small for gestational age in children."

So rather than stopping treatment before pregnancy and restarting it after birth, Wang and colleagues suggest this observational study – which can only point to correlations in data, not definitive causes – provides some encouraging evidence that continuing antipsychotic medication through pregnancy is a safe option, for both mother and baby.

With two lives are intertwined, decisions about using antipsychotic drugs in pregnancy are not straightforward, explains Simone Vigod, a psychiatric epidemiologist at the University of Toronto who co-authored a 2015 study that also found no evidence of an increased risk of pregnancy complications, including early births, for women on antipsychotic drugs.

"A woman with serious mental illness who discontinues her medication in pregnancy, out of concern for fetal harm, may jeopardize her own mental health and her ability to care for her child after delivery."

Medication aside, underlying maternal psychiatric disorders may well be associated with the risk of ADHD and ASD in children, the Hong Kong study found.

Among women who never needed antipsychotics, kids born to mothers with psychiatric disorders had higher odds of developing either ADHD or autism than children of mothers without any psychiatric diagnosis.

To dig deeper, the researchers also compared siblings from different pregnancies, a real strength of the study. This was used to account for genetic and environmental factors that could be shared among kids born to the same mum.

The matched siblings analysis showed that the risk of developing ADHD or autism was no different for kids of mothers on antipsychotic medication, as it was for their siblings born to the same mum, at another time – when she wasn't receiving treatment.

"These results suggest that maternal psychiatric disorders are associated with a higher risk of neurodevelopmental disorders rather than gestational exposure to antipsychotic drugs," the study authors conclude.

The research was published in JAMA Internal Medicine.