  We use high-resolution H {\alpha} images of 130 planetary nebulae (PNe) to
investigate whether there is a preferred orientation for PNe within the
Galactic Bulge. The orientations of the full sample have an uniform
distribution. However, at a significance level of 0.01, there is evidence for a
non-uniform distribution for those planetary nebulae with evident bipolar
morphology. If we assume that the bipolar PNe have an unimodal distribution of
the polar axis in Galactic coordinates, the mean Galactic position angle is
consistent with 90{\deg}, i.e. along the Galactic plane, and the significance
level is better than 0.001 (the equivalent of a 3.7{\sigma} significance level
for a Gaussian distribution).
  The shapes of PNe are related to angular momentum of the original star or
stellar system, where the long axis of the nebula measures the angular momentum
vector. In old, low-mass stars, the angular momentum is largely in binary
orbital motion. Consequently, the alignment of bipolar nebulae that we have
found indicates that the orbital planes of the binary systems are oriented
perpendicular to the Galactic plane. We propose that strong magnetic fields
aligned along the Galactic plane acted during the original star formation
process to slow the contraction of the star forming cloud in the direction
perpendicular to the plane. This would have produced a propensity for wider
binaries with higher angular momentum with orbital axes parallel to the
Galactic plane. Our findings provide the first indication of a strong,
organized magnetic field along the Galactic plane that impacted on the angular
momentum vectors of the resulting stellar population.
