You have the opportunity in the NIH biosketch to explain any gaps in your research productivity. Military service, family obligations, illness, and disability are the main reasons for gaps that quickly come to mind, but those are not the only reasons one may have for a gap. Explanation of any gap is not required, and many female researchers with whom I have discussed this topic have viscerally negative reactions to this part of the Personal Statement (PS) section of the biosketch. Usually the question is, will saying I took time off for family obligations affect the perception of me? The answer is it shouldn’t, but it might. Here’s how you handle it.
It’s unethical to take the sex of an applicant into consideration of expertise and experience pertinent to the role the person is serving on a particular project, which is the function of the biosketch, but it would be naïve to say it doesn’t happen. So, the answer here is, it’s incumbent upon you to decide whether the gap is long enough to necessitate explanation, especially if the reason for the gap is one you think would bias reviewers against you.
If you do decide to explain a gap, I would suggest you keep your explanation short and sweet like the example provided in the NIH sample biosketch: “During 2005-2006 my career was disrupted due to family obligations. However, upon returning to the field I immediately resumed my research project and collaborations and successfully competed for NIH support.” Note the follow-up information about post-absence NIH funding, an assertion that the seal of approval has already been granted so there really is nothing more to discuss. Boom. Done.