From my experience working with women on their fertility journeys, I’ve seen how thyroid health is a critical factor often overlooked. Many women think a TSH level of 4.0 is fine since it's within the lab's normal range, but when trying to conceive, that number can actually signal an underactive thyroid that might be affecting fertility. The thyroid acts as the body's thermostat, regulating metabolism and energy levels. When it’s not functioning optimally, the body may slow down non-essential processes — and unfortunately, reproduction often becomes less prioritized. This means that even subtle hypothyroidism, with TSH closer to 4.0, can create a hurdle on the path to conception. It’s important to approach lab results with a fertility optimization mindset, not just whether values fall within the typical range. For women TTC, aiming for a TSH closer to 2.5 or below can increase the chances of a healthy pregnancy. Treatments that improve thyroid function, such as lifestyle changes, natural supplements, or thyroid hormone replacement when appropriate, can make a big difference. I advise women in their fertility journey to discuss these nuances with their healthcare providers and request comprehensive thyroid testing, including free T3 and free T4, alongside TSH. Knowing the full picture allows for tailored interventions that support fertility better. Ultimately, understanding and addressing thyroid health early on can help avoid months or years of unexplained infertility. If you suspect thyroid issues may be a factor, consider booking a consultation to identify any fertility blindspots and create a personalized plan for your TTC journey.