Newcastle MP Catherine McKinnell, who was shadow attorney general for the party, has quit the Labour frontbench.
She will remain as MP for Newcastle North and return to backbench.
In a letter to Jeremy Corbyn she expressed three factors that had resulted in her resignation.
Ms McKinnell said: “I had my third child twelve months ago and have spent this past year combining care for him with both a General Election campaign and then returning to Parliament, including taking on the additional responsibility of a Shadow Cabinet post.
Ms McKinnell added: “The second [factor] is the reality of being a Shadow Cabinet member. It is perhaps not generally understood that this precludes an MP from speaking up in Parliament on issues outside the brief.
With recent events over the past few weeks concerning the Labour Party, Ms McKinnell expressed her concerns about “the direction and internal conflict within the Labour Party”.
She also expressed that she feels she “could better serve” her “constituents and the Labour Party from the backbenches“.
The Newcastle North MP is the fourth MP to quit (including Durham North’s Kevan Jones) since Corbyn’s cabinet reshuffle.