Drugs crush a woman's maternal instinct, new brain scans reveal.

Researchers from Baylor College of Medicine and the University of Iowa warn the finding is particularly concerning in light of America's drug addiction epidemic.

The team of obstetricians analyzed MRI scans of 36 mothers who suffered from substance use disorders.

They also videotaped them interacting with their infants at five months old.

Compared to healthy control groups, these mothers experienced a much weaker emotional response to their babies' smiling faces.

Researchers from Baylor College of Medicine and the University of Iowa found drug-addicted mothers are less maternal - and warn it is concerning in light of America's addiction epidemic

Lead author Dr Sohye Kim, assistant professor of obstetrics and gynecology at Baylor, said all 36 of the mothers found their children less intrinsically rewarding and more stress-provoking than other mothers.

'Unlike many mothers who find engaging with their infants to be a uniquely rewarding and gratifying experience, mothers with addictions, even when they are not actively using substances, may be less able to respond appropriately to their infants' cues,' Dr Kim added.

The mothers in the study recruited from an inpatient treatment facility for substance use disorders.

They underwent functional MRI scanning six months after delivery, while viewing happy and sad face images of their own infant.

Typically, seeing the smiling faces of their own infant is rewarding to mothers.

OPIOIDS ARE WILDLY OVER-PRESCRIBED AFTER C-SECTIONS Opioids are over-prescribed to women after a cesarean section in America, a new report warns. Most new mothers received double the amount of painkillers they need for a c-section - 40 pills rather than 20 - according to a study that looks at prescription rates in six parts of the US. That is a huge overflow, the researchers warn, give that a c-section delivery is the most common inpatient surgical procedure in the United States, with around 1.4 million c-sections performed each year. Crucially, they found women tended to take more pills if they had them, even if their pain levels were not strong. The review is one of the first attempts to collate data from providers and institutions nationwide, to offer a clear national picture. Opioids, most commonly oxycodone, are the standard pain medications prescribed to women following cesarean delivery. But the number of pills that are prescribed varies between providers and institutions, and there is little data regarding how much pain medication patients actually require to manage their pain.

This reward experience is what underlies and promotes the mother-infant attachment, which essentially motivates the mother to continue to care for the infant even when being a mother is extremely exhausting, Dr Kim said.

Previous studies have shown that mothers without addictions illustrate strong activations in the dopamine-associated brain reward regions when seeing their infants' happy faces.

However, researchers discovered that mothers with addictions showed a striking pattern of decreased activation in these same brain regions when viewing happy face images of their own infant.

'Our results are particularly noteworthy in two respects,' Dr Kim explained.

'First, they were specific to cues from the mothers' own infants and not unknown infants.

'Second, they were in response to what could arguably be considered the most rewarding cues from infants – their smiling faces.

'This is powerful because the smiling cue is probably the most rewarding cue one can get from one's own infant, yet the key reward regions appear to be shut down in response to these cues in mothers with addictions.'

The findings suggest a neurobiological reason for drug-addicted mothers finding it difficult to meet all their infants' needs.

'The transition to motherhood is inherently stressful,' Dr Kim said.

'It is the enhanced perceived reward value of infant cues, coupled with the sense of reward and pleasure experienced by the mother, that often help to sustain a mother's attention and responsiveness to her infant during a critical developmental period.

'When the functions of the dopamine- and oxytocin-associated maternal circuitry go awry, as our study has suggested here in the case of substance addictions, mothers may be compromised in their abilities to care for their infants, and the risk for abuse and neglect may rise.'

She added that public health officials need to start prioritizing research into the neurobiological relationship between substance addictions and impaired maternal responses.

Better understanding, she said, may facilitate earlier and more refined interventions to help support mothers with substance addictions and the infants in their care.