13. Employee benefit plans

Defined Contribution Plans

We have a defined contribution plan qualified under Section 401(k) of the Internal Revenue Code covering all U.S. employees and defined contribution plans for other Incyte employees in Europe. Employees may contribute a portion of their compensation, which is then matched by us, subject to certain limitations. Defined contribution expense for the three months ended March 31, 2019 and 2018 was $2.9 million and $2.7 million, respectively.

Defined Benefit Pension Plans

We have defined benefit pension plans for our employees in Europe which provide benefits to employees upon retirement, death or disability. The assets of the pension plans are held in collective investment accounts represented by the cash surrender value of an insurance policy and are classified as Level 2 within the fair value hierarchy.

The net periodic benefit cost was as follows (in thousands):


	Three Months Ended
	March 31,
	2019		2018
Service cost	$	1,263	$	1,079
Interest cost		84		71
Expected return on plan assets		(60)		(50)
Amortization of prior service cost		45		45
Amortization of actuarial losses		66		66
Net periodic benefit cost	$	1,398	$	1,211

The components of net periodic benefit cost other than the service cost component are included in other income (expense), net on the condensed consolidated statements of operations. We expect to contribute a total of $3.5 million to the pension plans in 2019 inclusive of the amounts contributed to the plan during the current period. As of March 31, 2019 and December 31, 2018, $15.8 million and $15.7 million, respectively, of accrued pension obligation is recorded in other long term liabilities on the condensed consolidated balance sheets.