United dominated the ball all afternoon at Westleigh Park and saw two players notch their first goals of the season while recording back-to-back clean sheets.
Shania Hayles almost made it three goals in three matches early on when she won the ball in Portsmouth's final third but her venomous effort only stung the palms of Eve Annets.
Just a minute later, captain Amber-Keegan Stobbs almost opened her account for the season when she was played through by Lois Joel. United's number four drove into the area, forcing Annets to push her fizzing effort behind for a corner.
Next, a Beth Lumsden corner - aided by the whistling wind - caused havoc in the Pompey box and saw Rachel Furness direct an effort off the crossbar just before the half-hour mark.
Just moments later Andrews was slipped in behind the Portsmouth backline but once again Annets stood firm, denying the number 17 before she put her second effort into the side-netting.
Less than a minute later and, after waves of early pressure, Andrews had her first goal for the club. A lovely scooped pass from McQuade allowed the summer signing to take one touch and fire her strike high into the roof of the net.
It took until the 48th minute for the hosts to register their first shot on target, but Emma Jones' effort from the outside the box was routinely saved by Claudia Moan.
Becky Langley made a triple substitution 11 minutes into the second half and it almost brought about an instant reward when McQuade's curling effort forced Annets into a diving save.
One of those substitutes was Katie Barker, who ghosted in behind the Portsmouth backline and was picked out by Stobbs but her snapshot was smartly saved by Annets at the near post.
With 20 minutes left to play, Pompey pushed to get back on level terms but instead, the Lasses extended their lead through McQuade.
A neat ball around the corner from Sophie Haywood unleashed Sibley down the right and her low cross found McQuade, with United's number 21 having the simple task of slotting home into an empty net from three yards out.
Portsmouth refused to go down without a fight as they pushed to create some late drama and almost succeeded. Megan Hornby worked some space on the edge of the area before watching on as her curling effort bounced behind off the crossbar.
Newcastle United Women: Claudia Moan, Lois Joel, Deanna Cooper (Liv Watt 80), Rachel Furness (Charlotte Potts 80), Demi Stokes, Elysia Boddy, Amber-Keegan Stobbs, Jasmine McQuade, Beth Lumsden (Isabella Sibley 56), Amy Andrews (Sophie Haywood 56), Shania Hayles (Katie Barker 56)
Subs not used: Hannah Hawkins, Georgia Gibson, Kacie Elson, Hannah Greenwood
