First to the question of whether it would save the company money to do this. In practice it probably would, but in theory the company would have an easier way to do it. The company is free to set the employee contribution to insurance premiums for spouse and kids. Some companies (maybe most) set this so once you are covering 2 dependents, additional dependents are no additional cost to the employee. However, kids are the least expensive people on insurance. So avoiding covering kids is not usually a major priority. And companies are not obligated to structure their premiums that way. They could charge per-dependent.
In my HR experience, it would make a heck of a lot more sense to approach this by restructuring premiums than by letting go more qualified workers and keeping less qualified workers, especially for any kind of skilled work. Insurance is a big expense, but it can be passed on to employees, and it’s not that big that it outweighs employee qualifications.
Also, I wouldn’t be so sure it would be legal, even if you managed to thread the needle of sex discrimination, age discrimination, disability discrimination (which does include having a disabled family member) and states with family status (married or parental) discrimination. Health insurance is also governed by ERISA, and doing just about anything to treat employees in the same job category unequally in any way jeopardizes the tax-exempt status of employer and employee health insurance costs.
If this were to happen, I think it would be most likely in a small company that knew of specific high-cost employees and was able to target them. As a general principle for a large company, it doesn’t make much HR sense, even if they could get away with it. There is a sense in which being older and higher in the organization goes along with a lot of things that make those employees more costly to the company, and having dependents is probably highly correlated with those factors.
md2000, there is a federal Pregnancy Discrimination Act. It comes down to saying pregnancy needs to be treated like any other serious but temporary health condition (NOT same as a disability), such as a broken leg. So you can’t fire someone for being pregnant if you wouldn’t also fire someone for having an injury or other temporary condition that prevented them from working. The Family and Medical Leave Act also provides the right to return to your job after pregnancy. Leave under the FMLA can be unpaid, however. Also, the FMLA doesn’t cover as many employers and employees as most other discrimination laws in the US. You are correct that severance isn’t mandated, although the payment of unemployment insurance premiums is.
Bottom line, my take is that this is unlikely to be happening on a large scale because kids aren’t the cost driver in health insurance, it is easier to restructure premiums than risk a bunch of lawsuits, and having the right employee in the job is usually worth more than the differential in insurance costs, especially if we are just talking about a couple of healthy kids. Small employers “conveniently” laying off known high-health-care consumers I believe happens more often.