Is there still gender bias towards women in science fields? If so, how would you suggest we overcome this?

There is in certain areas of medicine and/or science but women are catching up. For example, you will see more women in family practice and pediatrics , whereas you will see a male dominance in surgery and orthopedics. Things have come a long way though.

Much as it saddens me to say it, yes, there's still gender bias in science. Some of it is unconscious bias; for example, men and women often have different modes of communicating (a common example is that men tend to be more assertive in group situations, speaking up in class or in meetings more readily, etc.), and male leadership might subconsciously reward such behavior ("this person is a go-getter" or "this person is more like me"). It usually takes conscious effort to recognize and reverse that bias; not everyone does so.

Biases might also arise as a result of historical trends, e.g., women are historically underrepresented in fields like physics or surgery, which means male leadership has less direct and anecdotal evidence of women's performance, which leads them to subconsciously favor men unless the woman is particularly outstanding (higher bar). Even if the leadership is fully enlightened, the fact that a woman's cohort in college, medical school, or grad school is heavily male-dominated means she's at higher risk of running into the proverbial bad apple among her fellow students. There can also be a pack mentality in which otherwise-neutral males can be influenced by a bad apple to behave poorly ("just between us guys...").

Finally, and worst of all, the overt sexual harassment recently highlighted by the metoo movement is by no means limited to those in Hollywood and politics. Some very high-profile scientists (such as famed exoplanet hunter Geoff Marcy at UC Berkeley) have reportedly abused their positions of power for years if not decades. As far as I'm aware, there have been no trials, much less convictions (hence "reportedly"), but the sheer number and consistency of the claims is overwhelming; I believe the women.

As bad as all that sounds, the fact that more and more of these cases are coming to light and resulting in discipline and other systemic changes is encouraging...at least a little. Networking with other women, sharing stories, having the courage not only to report bad behavior but to keep escalating if the relevant authorities (department chairs, university ombudsmen, regents, etc.) fail to act, all will help move the needle. You can also reward those schools, hospitals, and other workplaces that have good reputations for acting quickly and decisively by spending your tuition dollars (or career time) on them and not on the bad apples. Universities definitely pay attention to their cash flow, even more than to bad publicity; workplaces similarly pay attention when they're no longer able to hire from 50% of the workforce, though maybe not quite to the same extent. Conferences like Grace Hopper can be a good way to start networking with other women in tech and finding out about the good and bad apples.