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Seasonal air pollution found to undermine IVF success

2025-04-17 - 2025-04

A recent study published in BMC Public Health explores the impact of seasonal fluctuations in fine particulate matter (PM) with a diameter of 2.5 µm or less (PM2.5) pollution on the outcomes of assisted reproductive technology (ART).
How does air pollution impact fertility?
The success of ART procedures can be affected by various factors, some of which include age, lifestyle, and genetics. To date, the impact of PM2.5 exposure on reproductive health, particularly ART outcomes, remains unclear.
Long-term exposure to PM2.5 air pollution significantly increases the risk of developing cardiovascular and respiratory diseases. Current evidence suggests that air pollution can also lead to reduced fertility rates and a greater risk of pregnancy complications such as reduced life birth rates. As a result, clinicians will often recommend limiting exposure to air pollution at least three months before initiating in vitro fertilization (IVF) treatment.
Despite these observations, few studies have investigation the impact of ambient PM2.5 levels on ART outcomes across seasons.
About the study
The current study was conducted at Shangqiu’s First People’s Hospital and included 13,476 patients who were treated for infertility issues with ART between February 2018 and December 2022. There were approximately 4,000 patients each with spring and summer treatments, as compared to 2,300 and 3,400 patients treated during winter and autumn, respectively.
The period during which PM2.5 levels were considered began at controlled ovarian stimulation and ended within 30 days of the pregnancy test. This period is considered a critical window of success for optimal oocyte and embryo development and implantation, respectively.
Study findings
With comparable gonadotropin use, multiple reproductive outcomes changed during all seasons and correlated with PM2.5 exposure. These included both early stages in the ART process like the number of oocytes and how many entered metaphase II (MII), the number of embryos suitable for transfer, and the number of good-quality embryos.
After adjusting for age and expected changes in seasonal rates, a significant negative association was observed between PM2.5 exposure and both pregnancy and life birth rates. PM2.5 exposure did not significantly affect miscarriage rates.
As compared to winter months, the spring and summer seasons were associated with a greater number of pregnancy rates for each transfer, with this difference statistically significant between winter and spring months. Live birth rates were also higher during the spring, summer, and autumn months.
Dissecting the mechanisms of PM2.5-mediated reproductive toxicity
Following the inhalation or ingestion of PM2.5, these particles can enter systemic circulation to reach the embryos and negatively impact optimal oocyte and embryo development. Several studies have reported that PM2.5 exposure induces the production of reactive oxygen species (ROS), mitochondrial dysfunction, DNA damage, and early apoptosis, all of which can diminish the quality of oocytes and prevent embryo implantation.
Within the female reproductive system, PM2.5 exposure can also damage endometrial cells, thereby inducing oxidative stress and inflammation that is not conducive for embryo attachment to the endometrial lining. PM2.5 exposure may also alter the expression of adhesion molecules, growth factors, and other substrates that are essential for successful embryo implantation.
In addition to the toxic effects of PM2.5 exposure on maternal reproductive health, various aspects of male fertility can similarly be impacted by PM2.5. Previously, researchers have reported that PM2.5 exposure reduces sperm quality and density by targeting the forehead box protein O1 (FOXO1), in addition to reducing testosterone levels and increasing inflammation within the testes.
Conclusions
Taken together, the study findings indicate a seasonal influence on the effects PM2.5 air pollution on ART outcomes, as live birth rates were significantly lower during the winter months as compared to other seasons of the year. Although the reproductive toxicity associated with PM2.5 is likely multifactorial, additional studies are needed to elucidate the exact mechanisms by which PM2.5 interferes with the potential success of ART treatments.

Can You Really Improve Your Egg Quality-and Fertility-With Lifestyle Changes?

2025-04-18 - 2025-04

Lots of talk about the biological clock swirls around numbers: You're born with all the eggs you'll ever have, and each year you lose another chunk, the decline ramping up precipitously as you reach and surpass the fateful age of 35. But the truth is, the reproductive potential of your ovaries isn't just a numbers game. The quality of your eggs, or whether they have a normal genetic makeup and optimal capacity to support the development of an embryo, plays a key role in determining if you ultimately get pregnant and have a healthy baby. It's only natural to wonder, then, how you might improve your egg quality for better odds.
Off the bat, you should know that a great deal of egg quality, much like quantity, is a function of age. As we grow older, "not only do we lose eggs, but the eggs we retain get more and more DNA mutations, which can lead to an egg with the wrong number of chromosomes," Anate Brauer, MD, a board-certified reproductive endocrinologist at RMA of New York, tells SELF. "That egg either won't fertilize, will fertilize and then not implant, or will fertilize, implant, and ultimately lead to miscarriage." Genetic abnormalities, health conditions like endometriosis and polycystic ovary syndrome (PCOS), and medical treatments like chemotherapy and radiation can also mess with DNA, compounding the age-related quality dropoff. And certain lifestyle factors that put the body in a stressful state can potentially have a similar impact, Dr. Brauer says (more on this to come).
DNA normalcy aside, other facets of an egg-like its shape and the function of its cellular structures-can also influence its potential to get fertilized and continually divide and grow into a healthy pregnancy, Brooke Rossi, MD, a board-certified reproductive endocrinologist at Ohio Reproductive Medicine, tells SELF. The workings of an egg's mitochondria, or energy-producing powerhouses, is especially key, as an egg requires a ton of fuel to turn into an embryo and ultimately develop into a human being. Factors like age, health, and yes, lifestyle can also futz with mitochondrial form and function, shifting your egg quality (for better or worse).
To what extent you can really modify any of these aspects of egg quality with lifestyle behaviors, however, is still scientifically fuzzy. There's also no test for egg quality-blood tests for anti-mullerian hormone (AMH) and follicle stimulating hormone (FSH) only give you a picture of your egg quantity, so "we don't know if there's a quality issue unless we pull the eggs out and look at them under a microscope, as with in-vitro fertilization (IVF)," Dr. Rossi says. But given the relevance of egg quality for a thriving pregnancy, it's worth considering behaviors with some research-backed potential to improve it-if only because this might be the one aspect of your fertility you can control, she notes. Read on to learn what the research says can (and can't) affect egg quality, and what you might do about it.
What are the lifestyle factors that could make a difference in your egg quality?
Behaviors that could potentially harm egg quality. As mentioned, doing certain not-so-supportive activities could hurt your eggs largely by causing what's known as oxidative stress in your body, which occurs when cell-damaging molecules called free radicals outnumber the helpful antioxidants that neutralize them. In particular, smoking, vaping, drinking alcohol, skipping sleep, using recreational drugs (like marijuana), and downing a ton of sugar may all contribute to an excess of those free-wheeling free radicals and impair your body's ability to defend against them. Over time, that can damage your cells, including your eggs, potentially impacting their DNA or the functioning of their mitochondria. And as noted, both changes can make it tougher to get pregnant or carry a healthy baby to term. And that's not even taking into account the other ways these behaviors might interfere with your overall fertility (outside of egg quality), like messing with certain hormone levels linked to ovulation and making it tougher for an embryo to implant in your uterus. But just like any negative fallout on your body from unhealthy habits, the effects of things like tobacco, alcohol, and sugar on your eggs are dose-dependent-meaning, they're more likely with chronic heavy use. For example, Dr. Rossi points to drinking boozy beverages every night as a risky choice, while Dr. Brauer notes that consistently eating processed foods (which tend to be amped with sugar) could pile on the oxidative stress. So it may be more helpful to think about tempering these behaviors, versus cutting them out completely. In the realm of smoking and vaping, it's easier to slip into frequent use-and fertility-damaging territory-given the addictive nature of nicotine. We've got comprehensive guides to quitting both smoking and vaping from people who've been there if you could use some support.

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Seasonal air pollution found to undermine IVF success

Can You Really Improve Your Egg Quality-and Fertility-With Lifestyle Changes?