Week 34 of pregnancy reduces breast cancer risk: study

Kosovan girls dressed as ballet dancers hold roses and perform in front of the National Theatre on October 10, 2018 during the International Breast Cancer Awareness Month, to raise awareness on breast cancer and to promote prevention. (AFP)
Updated 24 October 2018
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Week 34 of pregnancy reduces breast cancer risk: study

  • The link between pregnancy and breast cancer risk reduction is well known among medical researchers, who have suggested breast cells fundamentally alter their composition when a woman first falls pregnant and they prepare to produce milk

PARIS: Women’s bodies undergo a “striking” change during a specific week of pregnancy that can significantly reduce their risk of developing breast cancer later in life, scientists said Tuesday.
Previous research has highlighted how women under the age of 30 can reduce their risk of contracting breast cancer later in life by having a baby.
But a new study by experts in Denmark and Norway claims to have identified the precise week of pregnancy when the change occurs.
“If you deliver a child at week 33 you get the child, which is great, but you don’t get the bonus of having a lower risk of breast cancer for the rest of your life,” Mads Melbye, from the University of Copenhagen’s Department of Clinical Medicine and lead study author, told AFP.
“It’s a very distinct change in risk when you go from week 33 to week 34.”
A typical pregnancy lasts 40 weeks and a baby born before 37 weeks is considered premature.
Melbye and his team studied a huge database of nearly four million women in Denmark and Norway stretching back almost 40 years.
It listed the age at which each of them gave birth, how far into a pregnancy each birth occurred and whether or not they contracted breast cancer later in life.
They found that women who gave birth after 34 weeks had an average 13.6 percent lower risk of developing breast cancer compared to women who had no children.
For pregnancies that ended a week earlier, the reduction in risk — while still there — was only 2.4 percent.
Melbye said what changes in women during this vital week of gestation remains a mystery.
“We don’t know what that is, but knowing that you have to get to this point of the pregnancy makes it much easier for researchers to focus because we have to know what happens around that week to understand this,” he said.
He said it may be possible a woman’s body sends a signal after 34 weeks of pregnancy to boost immunity against environmental causes of breast cancer.
“To the best of our knowledge it must have something to do with a specific biological effect that the cells reach at 34 weeks.”

The link between pregnancy and breast cancer risk reduction is well known among medical researchers, who have suggested breast cells fundamentally alter their composition when a woman first falls pregnant and they prepare to produce milk.
But Melbye and his team found that a second or third pregnancy of at least 34 weeks reduced the risk of breast cancer even further.
This held true even in women who experienced stillbirths after 34 weeks, meaning the change is unlikely to be linked to breastfeeding.
Authors of the study, published in the journal Nature Communications, said it would allow scientists to better probe the link between pregnancy and breast cancer risk by focusing on a narrow window during which the “striking” change occurs.
Although the reduction of risk is dramatic, there’s a catch: researchers found that the additional protection against breast cancer only comes in women under 30.
“It’s not only the first childbirth; every childbirth has its own reduction in breast cancer risk but there’s a trick to this: You have to have your kids before you turn 29,” said Melbye.
“Because after that age there’s no extra bonus in breast cancer risk (reduction).”


Is sourdough Saudi Arabia’s latest craft food?

Updated 07 February 2026
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Is sourdough Saudi Arabia’s latest craft food?

  • Saudi home bakers point to a practice that was once routine, not artisanal
  • Naturally fermented bread reflects a broader shift toward process-driven, premium food culture

ALKHOBAR: Sourdough has started to shift from a niche interest into a mainstream feature of home kitchens, cafes and specialty bakeries across the Kingdom.

The rise of sourdough is part of a wider shift in Saudi Arabia’s food landscape, where artisanal production and slower preparation methods are gaining traction.

Specialty coffee seems to have set the early template for this transition, normalizing premium pricing, craftsmanship and an interest in process.

The rise of sourdough is part of a wider shift in Saudi Arabia’s food landscape, where artisanal production and slower preparation methods are gaining traction. (Supplied/creativecommons)

Bread is now undergoing a similar shift, with fermentation replacing extraction and roasting as the central point of differentiation.

In both cases, the appeal is rooted in the product’s perceived authenticity, reduced additives, and a clearer link between raw ingredients and final consumption.

Home bakers in Riyadh, Jeddah and the Eastern Province have adapted natural yeast cultures to the Saudi environment, adjusting feeding schedules, hydration ratios, and fermentation times to accommodate higher temperatures and lower humidity in the summer months.

HIGHLIGHTS

• Home bakers in Riyadh, Jeddah and the Eastern Province have adapted natural yeast cultures to the Saudi environment.

• They adjust feeding schedules, hydration ratios, and fermentation times to accommodate higher temperatures and lower humidity in the summer months.

Cafes and specialty bakeries have responded by adding sourdough loaves, baguettes and focaccia to their menus, often positioned as premium alternatives to conventional commercial bread.

For younger home bakers, the appeal lies in the craft and the learning curve rather than nostalgia. “It feels more real and more intentional,” home baker Sarah Al-Almaei told Arab News. She began experimenting with natural yeast at home after watching starter tutorials online.

The technical aspect — hydration percentages, fermentation control and starter maintenance — has become content in its own right, with TikTok and Instagram compressing trial-and-error learning into short videos and recipe cards.

But the practice of maintaining a natural yeast culture is not new in Saudi Arabia. Long before sourdough became a global trend, Saudi households kept what was commonly referred to as the “mother dough,” a natural yeast starter fed and used daily.

“We used to maintain it every day and bake with it,” said Hessa Al-Otaibi, 56, a Saudi home baker with more than four decades’ experience. “People today call it sourdough. For us, it was simply bread.”

Her comment highlights a cultural continuity that has remained largely unrecognized, partly because the practice was not framed as artisanal or health-oriented, but as a routine household function.

The modern sourdough trend differs in its market positioning. While the older model was practical and domestic, the current model is commercial, aesthetic and often health-coded. Bakeries justify higher pricing through longer fermentation times, higher ingredient costs and smaller batch production.

Consumers justify their purchases through digestibility, perceived health benefits, flavor and product integrity.

“Once you get used to it, it’s hard to go back,” said Amina Al-Zahrani, a regular buyer of sourdough from specialty bakeries in Alkhobar.

Digestibility and texture are often cited as reasons for substitution, especially among buyers who report discomfort from standard commercial bread.

Another consumer, Majda Al-Ansari, says sourdough has become part of her weekly routine, noting that availability and quality have improved significantly in the past year.

The social media component has played an outsized role in accelerating adoption. Home bakers document starter feeding cycles, cold proofing and first bakes, turning a once-private domestic process into visible public content.

This has also created micro-markets of home-based sellers, where individual bakers offer loaves to local buyers, often fulfilling orders through direct messaging.

What remains to be seen is how far the trend will scale. If specialty bakeries continue to expand and consumers maintain willingness to pay premium prices, sourdough could establish a long-term place in Saudi food culture.

If not, it may revert to a smaller niche of committed home bakers and specialty cafes. For now, however, sourdough occupies an unusual position: both a newly fashionable trend and a quiet continuation of an older Saudi baking practice.